--- a/.cron.yml
+++ b/.cron.yml
@@ -1,14 +1,16 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 # Definitions for jobs that run periodically.  For details on the format, see
 # `taskcluster/taskgraph/cron/schema.py`.  For documentation, see
 # `taskcluster/docs/cron.rst`.
 
----
-
 jobs:
     - name: nightly-desktop
       job:
           type: decision-task
           treeherder-symbol: Nd
           target-tasks-method: nightly_desktop
       run-on-projects:
           - comm-central

--- a/.taskcluster.yml
+++ b/.taskcluster.yml
@@ -1,9 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 ---
+# yamllint disable rule:indentation
 # This file is rendered via JSON-e by
 # - mozilla-taskcluster - See
 #   https://docs.taskcluster.net/reference/integrations/mozilla-taskcluster/docs/taskcluster-yml
 #   {
 #     tasks_for: 'hg-push',
 #     push: {owner, comment, pushlog_id, pushdate},
 #     repository: {url, project, level},
 #     now,

--- a/.yamllint
+++ b/.yamllint
@@ -1,8 +1,12 @@
 ---
 extends: default
 
 rules:
   document-end:
      present: false
+  document-start:
+     present: true
+  indentation:
+     spaces: 4
   # Checks currently failing
   line-length: disable

--- a/mail/config/whats_new_page.yml
+++ b/mail/config/whats_new_page.yml
@@ -1,7 +1,6 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
 ---
--   type: product-details
-    url: https://live.thunderbird.net/thunderbird/releasenotes?locale=%LOCALE%&version={version}&channel={release-type}
+- type: product-details
+  url: https://live.thunderbird.net/thunderbird/releasenotes?locale=%LOCALE%&version={version}&channel={release-type}

--- a/taskcluster/.yamllint
+++ b/taskcluster/.yamllint
@@ -1,12 +1,12 @@
 ---
 extends: default
 
 rules:
   document-end:
      present: false
   document-start:
-     present: false
+     present: true
+  indentation:
+     spaces: 4
   # Checks currently failing
   line-length: disable
-  indentation:
-     spaces: 4

--- a/taskcluster/ci/balrog/kind.yml
+++ b/taskcluster/ci/balrog/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.balrog_submit:transforms
     - taskgraph.transforms.scriptworker:add_balrog_scopes
     - taskgraph.transforms.task:transforms
 

--- a/taskcluster/ci/beetmover-checksums/kind.yml
+++ b/taskcluster/ci/beetmover-checksums/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.beetmover_checksums:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/beetmover-l10n/kind.yml
+++ b/taskcluster/ci/beetmover-l10n/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.beetmover_l10n:transforms
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.beetmover:transforms
     - taskgraph.transforms.task:transforms
     - comm_taskgraph:remove_widevine_and_stub_installer

--- a/taskcluster/ci/beetmover-repackage/kind.yml
+++ b/taskcluster/ci/beetmover-repackage/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.multi_dep:loader
 
 group-by: single-locale
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.beetmover_repackage_l10n:transforms
     - taskgraph.transforms.beetmover_repackage:transforms

--- a/taskcluster/ci/beetmover-source/kind.yml
+++ b/taskcluster/ci/beetmover-source/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.beetmover:transforms
     - taskgraph.transforms.beetmover_source:transforms
     - taskgraph.transforms.task:transforms
 

--- a/taskcluster/ci/build-signing/kind.yml
+++ b/taskcluster/ci/build-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.build_signing:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.build_signing:transforms
     - taskgraph.transforms.signing:transforms
     - taskgraph.transforms.task:transforms
     - comm_taskgraph:remove_widevine_and_stub_installer

--- a/taskcluster/ci/build/kind.yml
+++ b/taskcluster/ci/build/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 kind-dependencies:
     - toolchain
 
 transforms:
     - taskgraph.transforms.build:transforms
     - taskgraph.transforms.build_attrs:transforms

--- a/taskcluster/ci/build/linux.yml
+++ b/taskcluster/ci/build/linux.yml
@@ -1,8 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 linux64/opt:
     description: "Linux64 Opt"
     index:
         product: thunderbird
         job-name: linux64-opt
     treeherder:
         platform: linux64/opt
         symbol: B

--- a/taskcluster/ci/build/macosx.yml
+++ b/taskcluster/ci/build/macosx.yml
@@ -1,8 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 macosx64/debug:
     description: "MacOS X x64 Cross-compile"
     index:
         product: thunderbird
         job-name: macosx64-debug
     treeherder:
         platform: osx-cross/debug
         symbol: B

--- a/taskcluster/ci/build/windows.yml
+++ b/taskcluster/ci/build/windows.yml
@@ -1,8 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 job-defaults:
     run:
         using: mozharness
         use-caches: false
         comm-checkout: true
         config-paths:
             - comm/mozharness
 

--- a/taskcluster/ci/checksums-signing/kind.yml
+++ b/taskcluster/ci/checksums-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.checksums_signing:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/config.yml
+++ b/taskcluster/ci/config.yml
@@ -1,8 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 trust-domain: comm
 project-repo-param-prefix: comm_
 product-dir: comm/mail
 
 treeherder:
     group-names:
         'X': 'Xpcshell tests'
         'Z': 'MozMill tests'

--- a/taskcluster/ci/docker-image/kind.yml
+++ b/taskcluster/ci/docker-image/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: comm_taskgraph:reference_loader
 base-path: taskcluster/ci
 
 kind-dependencies:
     - packages
 
 jobs:
     - debian7-amd64-build

--- a/taskcluster/ci/fetch/kind.yml
+++ b/taskcluster/ci/fetch/kind.yml
@@ -1,6 +1,6 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: comm_taskgraph:reference_loader
 base-path: taskcluster/ci

--- a/taskcluster/ci/mar-signing-l10n/kind.yml
+++ b/taskcluster/ci/mar-signing-l10n/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.mar_signing:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/mar-signing/kind.yml
+++ b/taskcluster/ci/mar-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.mar_signing:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/nightly-l10n-signing/kind.yml
+++ b/taskcluster/ci/nightly-l10n-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.nightly_l10n_signing:transforms
     - taskgraph.transforms.signing:transforms
     - taskgraph.transforms.task:transforms
     - comm_taskgraph:remove_widevine_and_stub_installer

--- a/taskcluster/ci/nightly-l10n/kind.yml
+++ b/taskcluster/ci/nightly-l10n/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.multi_dep:loader
 
 group-by: platform
 
 transforms:
     - taskgraph.transforms.l10n:transforms
     - taskgraph.transforms.use_toolchains:transforms
     - taskgraph.transforms.job:transforms

--- a/taskcluster/ci/packages/kind.yml
+++ b/taskcluster/ci/packages/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: comm_taskgraph:reference_loader
 base-path: taskcluster/ci
 
 jobs:
     - deb7-32-atk
     - deb7-32-gdk-pixbuf
     - deb7-32-glib
     - deb7-32-gtk3

--- a/taskcluster/ci/post-balrog-dummy/kind.yml
+++ b/taskcluster/ci/post-balrog-dummy/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.per_platform_dummy:transforms
     - taskgraph.transforms.reverse_chunk_deps:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/post-beetmover-checksums-dummy/kind.yml
+++ b/taskcluster/ci/post-beetmover-checksums-dummy/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.reverse_chunk_deps:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:
     - beetmover-checksums

--- a/taskcluster/ci/post-beetmover-dummy/kind.yml
+++ b/taskcluster/ci/post-beetmover-dummy/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.per_platform_dummy:transforms
     - taskgraph.transforms.reverse_chunk_deps:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-balrog-scheduling/kind.yml
+++ b/taskcluster/ci/release-balrog-scheduling/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release:run_on_releases
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.scriptworker:add_balrog_scopes
     - taskgraph.transforms.task:transforms
 

--- a/taskcluster/ci/release-balrog-submit-toplevel/kind.yml
+++ b/taskcluster/ci/release-balrog-submit-toplevel/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release:run_on_releases
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.scriptworker:add_balrog_scopes
     - taskgraph.transforms.balrog_toplevel:transforms
     - taskgraph.transforms.task:transforms

--- a/taskcluster/ci/release-beetmover-push-to-release/kind.yml
+++ b/taskcluster/ci/release-beetmover-push-to-release/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.beetmover_push_to_release:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-beetmover-source-checksums/kind.yml
+++ b/taskcluster/ci/release-beetmover-source-checksums/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.beetmover_source_checksums:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-bouncer-aliases/kind.yml
+++ b/taskcluster/ci/release-bouncer-aliases/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.bouncer_aliases:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-bouncer-check/kind.yml
+++ b/taskcluster/ci/release-bouncer-check/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 kind-dependencies:
     - release-beetmover-push-to-release
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.bouncer_check:transforms

--- a/taskcluster/ci/release-bouncer-sub/kind.yml
+++ b/taskcluster/ci/release-bouncer-sub/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.bouncer_submission:transforms
     - taskgraph.transforms.task:transforms
 
 job-defaults:
     description: release bouncer submission job

--- a/taskcluster/ci/release-final-verify/kind.yml
+++ b/taskcluster/ci/release-final-verify/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 kind-dependencies:
     - release-bouncer-check
     - release-update-verify-config
 
 transforms:
     - taskgraph.transforms.release_deps:transforms

--- a/taskcluster/ci/release-generate-checksums-beetmover/kind.yml
+++ b/taskcluster/ci/release-generate-checksums-beetmover/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.release_generate_checksums_beetmover:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:
     - release-generate-checksums-signing

--- a/taskcluster/ci/release-generate-checksums-signing/kind.yml
+++ b/taskcluster/ci/release-generate-checksums-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 kind-dependencies:
     - release-generate-checksums
 
 transforms:
     - taskgraph.transforms.release_generate_checksums_signing:transforms
     - taskgraph.transforms.task:transforms

--- a/taskcluster/ci/release-generate-checksums/kind.yml
+++ b/taskcluster/ci/release-generate-checksums/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 kind-dependencies:
     - beetmover-source
     - post-beetmover-checksums-dummy
 
 transforms:
     - taskgraph.transforms.build:transforms

--- a/taskcluster/ci/release-mark-as-shipped/kind.yml
+++ b/taskcluster/ci/release-mark-as-shipped/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.release_mark_as_shipped:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-notify-promote/kind.yml
+++ b/taskcluster/ci/release-notify-promote/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.release_notifications:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-notify-push/kind.yml
+++ b/taskcluster/ci/release-notify-push/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.release_notifications:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-notify-ship/kind.yml
+++ b/taskcluster/ci/release-notify-ship/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.release_notifications:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-source-checksums-signing/kind.yml
+++ b/taskcluster/ci/release-source-checksums-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.source_checksums_signing:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/release-source-signing/kind.yml
+++ b/taskcluster/ci/release-source-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.build_signing:transforms
     - taskgraph.transforms.signing:transforms
     - taskgraph.transforms.task:transforms
 

--- a/taskcluster/ci/release-source/kind.yml
+++ b/taskcluster/ci/release-source/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.build:transforms
     - taskgraph.transforms.build_attrs:transforms
     - taskgraph.transforms.build_lints:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms

--- a/taskcluster/ci/release-update-verify-config/kind.yml
+++ b/taskcluster/ci/release-update-verify-config/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.update_verify_config:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms
 
 job-defaults:

--- a/taskcluster/ci/release-update-verify/kind.yml
+++ b/taskcluster/ci/release-update-verify/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 kind-dependencies:
     - post-balrog-dummy
     - post-beetmover-dummy
     - release-balrog-submit-toplevel
     - release-update-verify-config
 

--- a/taskcluster/ci/release-version-bump/kind.yml
+++ b/taskcluster/ci/release-version-bump/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.release_deps:transforms
     - taskgraph.transforms.release_version_bump:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/repackage-l10n/kind.yml
+++ b/taskcluster/ci/repackage-l10n/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.repackage_l10n:transforms
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.repackage:transforms
     - taskgraph.transforms.use_toolchains:transforms
     - taskgraph.transforms.job:transforms

--- a/taskcluster/ci/repackage-msi/kind.yml
+++ b/taskcluster/ci/repackage-msi/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.repackage:transforms
     - taskgraph.transforms.use_toolchains:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms

--- a/taskcluster/ci/repackage-signing-l10n/kind.yml
+++ b/taskcluster/ci/repackage-signing-l10n/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.repackage_signing:transforms
     - taskgraph.transforms.task:transforms
     - comm_taskgraph:remove_widevine_and_stub_installer
 

--- a/taskcluster/ci/repackage-signing-msi/kind.yml
+++ b/taskcluster/ci/repackage-signing-msi/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.repackage_signing:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies:

--- a/taskcluster/ci/repackage-signing/kind.yml
+++ b/taskcluster/ci/repackage-signing/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.repackage_signing:transforms
     - taskgraph.transforms.task:transforms
     - comm_taskgraph:remove_widevine_and_stub_installer
 

--- a/taskcluster/ci/repackage/kind.yml
+++ b/taskcluster/ci/repackage/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.name_sanity:transforms
     - taskgraph.transforms.repackage:transforms
     - taskgraph.transforms.use_toolchains:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms

--- a/taskcluster/ci/repo-update/kind.yml
+++ b/taskcluster/ci/repo-update/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.repo_update:transforms
     - taskgraph.transforms.task:transforms
 
 
 job-defaults:

--- a/taskcluster/ci/source-test/kind.yml
+++ b/taskcluster/ci/source-test/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.transform:loader
 
 transforms:
     - taskgraph.transforms.try_job:transforms
     - taskgraph.transforms.source_test:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms
 

--- a/taskcluster/ci/source-test/mozlint.yml
+++ b/taskcluster/ci/source-test/mozlint.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 job-defaults:
     always-target: true
     treeherder:
         kind: test
         tier: 1
     worker-type: t-linux-xlarge
     worker:
         docker-image: {in-tree: "lint"}
@@ -51,17 +51,21 @@ eslint:
             - 'tools/lint/eslint/eslint-plugin-spidermonkey-js/**'
 
 yaml:
     description: yamllint run over the taskcluster configuration
     platform: lint/opt
     treeherder:
         symbol: yaml
     run:
-        mach: lint -f treeherder -l yaml -n comm/taskcluster comm/.taskcluster.yml
+        mach: >
+            lint -f treeherder -l yaml -n
+            comm/mail/config
+            comm/taskcluster
+            comm/.*.yml
     when:
         files-changed:
             - 'comm/**/*.yml'
             - 'comm/**/*.yaml'
             - '**/.ymllint'
 
 py-flake8:
     description: flake8 run over the thunderbird codebase

--- a/taskcluster/ci/test/kind.yml
+++ b/taskcluster/ci/test/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.test:loader
 
 kind-dependencies:
     - build
     - build-signing
     - fetch
     - toolchain
 

--- a/taskcluster/ci/test/test-platforms.yml
+++ b/taskcluster/ci/test/test-platforms.yml
@@ -1,22 +1,25 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 # This file maps build platforms to test platforms.  In some cases, a
 # single build may be tested on multiple test platforms, but a single test
 # platform can only link to one build platform.  Both build and test platforms
 # are represented as <platform>/<type>, where <type> is what Treeherder calls a
 # collection.
 #
 # Each test platform further specifies the set of tests that will be scheduled
 # for the platform, referring to tests defined in test-sets.yml.
 #
 # Note that set does not depend on the tree; tree-dependent job selection
 # should be performed in the target task selection phase of task-graph
 # generation.
 
-
 # Linux platforms (matching /linux.*/)
 
 linux64/opt:
     build-platform: linux64/opt
     test-sets:
         - common-tests
         - optimized-tests
 

--- a/taskcluster/ci/test/test-sets.yml
+++ b/taskcluster/ci/test/test-sets.yml
@@ -1,8 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 # Each key in this file specifies a set of tests to run.  Different test sets
 # may, for example, be bound to different test platforms.
 #
 # Note that set does not depend on the tree; tree-dependent job selection
 # should be performed in the target task selection phase of task-graph
 # generation.
 #
 # A test set has a name, and a list of tests that it contains.

--- a/taskcluster/ci/test/tests.yml
+++ b/taskcluster/ci/test/tests.yml
@@ -1,8 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
 # Each stanza here describes a particular test suite or sub-suite.  These are
 # processed through the transformations described in kind.yml to produce a
 # bunch of tasks.  See the schema in `taskcluster/taskgraph/transforms/tests.py`
 # for a description of the fields used here.
 
 # Note that these are in lexical order, as enforced by the task loader.
 
 # Adding a new test type or running tests on a new platform? Be sure to review

--- a/taskcluster/ci/toolchain/kind.yml
+++ b/taskcluster/ci/toolchain/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: comm_taskgraph:reference_loader
 base-path: taskcluster/ci
 
 kind-dependencies:
     - fetch
 
 jobs:
     - linux64-binutils

--- a/taskcluster/ci/upload-symbols/kind.yml
+++ b/taskcluster/ci/upload-symbols/kind.yml
@@ -1,12 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
+---
 loader: taskgraph.loader.single_dep:loader
 
 transforms:
     - taskgraph.transforms.upload_symbols:transforms
     - taskgraph.transforms.job:transforms
     - taskgraph.transforms.task:transforms
 
 kind-dependencies: