--- a/mail/moz.configure
+++ b/mail/moz.configure
@@ -6,16 +6,18 @@
 
 set_config('MOZ_THUNDERBIRD', True)
 set_define('MOZ_THUNDERBIRD', True)
 
 set_define('MOZ_SEPARATE_MANIFEST_FOR_THEME_OVERRIDES', True)
 
 imply_option('MOZ_PLACES', True)
 imply_option('MOZ_ALLOW_LEGACY_EXTENSIONS', True)
+imply_option('MOZ_DEDICATED_PROFILES', True)
+imply_option('MOZ_BLOCK_PROFILE_DOWNGRADE', True)
 
 
 @depends(application)
 def is_comm_topdir(app):
     return not app[0].startswith('comm/')
 
 
 set_config('MOZ_IS_COMM_TOPDIR', is_comm_topdir)