--- a/mail/locales/en-US/chrome/messenger/am-offline.dtd
+++ b/mail/locales/en-US/chrome/messenger/am-offline.dtd
@@ -6,17 +6,19 @@
 <!ENTITY offlineNotDownload.accesskey "M">
 <!ENTITY kb.label "KB">
 <!ENTITY daysOld.label "days old">
 <!ENTITY message.label "messages">
 <!ENTITY nntpNotDownloadRead.label "Read messages">
 <!ENTITY nntpNotDownloadRead.accesskey "d">
 <!ENTITY nntpDownloadMsg.label "Messages more than">
 <!ENTITY nntpDownloadMsg.accesskey "e">
-<!ENTITY retentionCleanup.label "To recover disk space, old messages can be permanently deleted">
+<!ENTITY retentionCleanup.label "To recover disk space, old messages can be permanently deleted.">
+<!ENTITY retentionCleanupImap.label "To recover disk space, old messages can be permanently deleted, both local copies and originals on the remote server.">
+<!ENTITY retentionCleanupPop.label "To recover disk space, old messages can be permanently deleted, including originals on the remote server.">
 <!ENTITY retentionKeepMsg.label "Delete messages more than">
 <!ENTITY retentionKeepMsg.accesskey "t">
 <!ENTITY retentionKeepAll.label "Don't delete any messages">
 <!ENTITY retentionKeepAll.accesskey "n">
 <!ENTITY retentionKeepNew.label "Delete all but the last">
 <!ENTITY retentionKeepNew.accesskey "b">
 <!ENTITY retentionKeepUnread.label "Always delete read messages">
 <!ENTITY retentionKeepUnread.accesskey "w">

--- a/mail/locales/en-US/chrome/messenger/folderProps.dtd
+++ b/mail/locales/en-US/chrome/messenger/folderProps.dtd
@@ -49,17 +49,19 @@
 <!ENTITY folderRebuildSummaryFile.accesskey      "R">
 <!ENTITY folderRebuildSummaryFileTip.label       "Rebuild Summary File"> 
      
 <!ENTITY retention.label "Retention Policy">
 <!ENTITY retentionUseDefault.label  "Use server defaults">
 <!ENTITY retentionUseDefault.accesskey "d">
 <!ENTITY daysOld.label "days old">
 <!ENTITY message.label "messages">
-<!ENTITY retentionCleanup.label "To recover disk space, old messages can be permanently deleted">
+<!ENTITY retentionCleanup.label "To recover disk space, old messages can be permanently deleted.">
+<!ENTITY retentionCleanupImap.label "To recover disk space, old messages can be permanently deleted, both local copies and originals on the remote server.">
+<!ENTITY retentionCleanupPop.label "To recover disk space, old messages can be permanently deleted, including originals on the remote server.">
 <!ENTITY retentionDeleteMsg.label "Delete messages more than">
 <!ENTITY retentionDeleteMsg.accesskey "m">
 <!ENTITY retentionKeepAll.label "Don't delete any messages">
 <!ENTITY retentionKeepAll.accesskey "A">
 <!ENTITY retentionKeepNew.label "Delete all but the last">
 <!ENTITY retentionKeepNew.accesskey "l">
 <!ENTITY retentionKeepUnread.label "Always delete read messages">
 <!ENTITY retentionKeepUnread.accesskey "r">

--- a/mailnews/base/prefs/resources/content/am-offline.xul
+++ b/mailnews/base/prefs/resources/content/am-offline.xul
@@ -108,17 +108,19 @@
         <textbox wsm_persist="true" id="nntp.downloadMsgMin"
                  type="number" min="1" size="2" value="30"
                  aria-labelledby="nntp.downloadMsg nntp.downloadMsgMin daysOldLabel"/>
         <label value="&daysOld.label;" control="nntp.downloadMsgMin" id="daysOldLabel"/>
     </hbox>
 
     <vbox align="start">
     <separator hidefor="none,rss"/>
-    <label id="retentionDescription" hidefor="" class="desc" control="retention.keepMsg">&retentionCleanup.label;</label>
+    <label id="retentionDescription" hidefor="imap,pop3" class="desc" control="retention.keepMsg">&retentionCleanup.label;</label>
+    <label id="retentionDescriptionImap" hidefor="movemail,pop3,nntp,none,rss" class="desc" control="retention.keepMsg">&retentionCleanupImap.label;</label>
+    <label id="retentionDescriptionPop" hidefor="movemail,imap,nntp,none,rss" class="desc" control="retention.keepMsg">&retentionCleanupPop.label;</label>
 
     <radiogroup wsm_persist="true" hidefor="" id="retention.keepMsg" class="indent">
         <radio wsm_persist="true" id="retention.keepAllMsg" value="1" accesskey="&retentionKeepAll.accesskey;"
             label="&retentionKeepAll.label;" oncommand="onCheckKeepMsg();"/>
         <hbox flex="1" align="center">
             <radio wsm_persist="true" id="retention.keepNewMsg" accesskey="&retentionKeepNew.accesskey;" 
                 value="3" label="&retentionKeepNew.label;" oncommand="onCheckKeepMsg();"/>
             <textbox wsm_persist="true" id="retention.keepNewMsgMin"

--- a/mailnews/base/resources/content/folderProps.xul
+++ b/mailnews/base/resources/content/folderProps.xul
@@ -107,17 +107,19 @@
         <button iscontrolcontainer="true" label="&folderRebuildSummaryFile.label;" 
                oncommand="RebuildSummaryInformation();" accesskey="&folderRebuildSummaryFile.accesskey;" 
                 tooltiptext="&folderRebuildSummaryFileTip.label;"
                align="center"/>
       </hbox>
     </vbox>
 
     <vbox align="start">
-    <description class="desc">&retentionCleanup.label;</description>
+    <description hidable="true" hidefor="imap,pop3" class="desc">&retentionCleanup.label;</description>
+    <description hidable="true" hidefor="movemail,pop3,rss,none,nntp" class="desc">&retentionCleanupImap.label;</description>
+    <description hidable="true" hidefor="movemail,imap,rss,none,nntp" class="desc">&retentionCleanupPop.label;</description>
 
         <hbox align="center" class="indent">
           <checkbox wsm_persist="true" id="retention.useDefault" accesskey="&retentionUseDefault.accesskey;"
               label="&retentionUseDefault.label;" checked="true" oncommand="onUseDefaultRetentionSettings()"/>
         </hbox>
         <vbox class="indent">
           <hbox class="indent">
             <radiogroup wsm_persist="true" id="retention.keepMsg" aria-labelledby="retention.useDefault">

--- a/suite/locales/en-US/chrome/mailnews/folderProps.dtd
+++ b/suite/locales/en-US/chrome/mailnews/folderProps.dtd
@@ -49,17 +49,19 @@
 <!ENTITY folderRebuildSummaryFile.accesskey      "R">
 <!ENTITY folderRebuildSummaryFileTip.label       "Rebuild Summary File">
 
 <!ENTITY retention.label "Retention Policy">
 <!ENTITY retentionUseDefault.label "Use server defaults">
 <!ENTITY retentionUseDefault.accesskey "d">
 <!ENTITY daysOld.label "days old">
 <!ENTITY message.label "messages">
-<!ENTITY retentionCleanup.label "Keep:">
+<!ENTITY retentionCleanup.label "Keep messages:">
+<!ENTITY retentionCleanupImap.label "Keep messages, both the local copies and their originals on the server:">
+<!ENTITY retentionCleanupPop.label "Keep messages, including their originals on the server:">
 <!ENTITY retentionDeleteMsg.label "Delete messages more than">
 <!ENTITY retentionDeleteMsg.accesskey "m">
 <!ENTITY retentionKeepAll.label "All messages">
 <!ENTITY retentionKeepAll.accesskey "A">
 <!ENTITY retentionKeepNew.label "The newest">
 <!ENTITY retentionKeepNew.accesskey "n">
 <!ENTITY retentionKeepUnread.label "Only unread messages">
 <!ENTITY retentionKeepUnread.accesskey "u">

--- a/suite/locales/en-US/chrome/mailnews/pref/am-offline.dtd
+++ b/suite/locales/en-US/chrome/mailnews/pref/am-offline.dtd
@@ -6,17 +6,19 @@
 <!ENTITY offlineNotDownload.accesskey "M">
 <!ENTITY kb.label "KB">
 <!ENTITY daysOld.label "days old">
 <!ENTITY message.label "messages">
 <!ENTITY nntpNotDownloadRead.label "Read messages">
 <!ENTITY nntpNotDownloadRead.accesskey "d">
 <!ENTITY nntpDownloadMsg.label "Messages more than">
 <!ENTITY nntpDownloadMsg.accesskey "e">
-<!ENTITY retentionCleanup.label "To recover disk space, old messages can be permanently deleted">
+<!ENTITY retentionCleanup.label "To recover disk space, old messages can be permanently deleted.">
+<!ENTITY retentionCleanupImap.label "To recover disk space, old messages can be permanently deleted, both the local copies and their originals on the server.">
+<!ENTITY retentionCleanupPop.label "To recover disk space, old messages can be permanently deleted, including their originals on the server.">
 <!ENTITY retentionKeepMsg.label "Delete messages more than">
 <!ENTITY retentionKeepMsg.accesskey "t">
 <!ENTITY retentionKeepAll.label "Don't delete any messages">
 <!ENTITY retentionKeepAll.accesskey "n">
 <!ENTITY retentionKeepNew.label "Delete all but the last">
 <!ENTITY retentionKeepNew.accesskey "b">
 <!ENTITY retentionKeepUnread.label "Always delete read messages">
 <!ENTITY retentionKeepUnread.accesskey "w">