diff --git a/mozilla/mailnews/imap/src/nsImapProtocol.cpp b/mozilla/mailnews/imap/src/nsImapProtocol.cpp
index 26e33ec26bc..772260894af 100644
--- a/mozilla/mailnews/imap/src/nsImapProtocol.cpp
+++ b/mozilla/mailnews/imap/src/nsImapProtocol.cpp
@@ -316,6 +316,7 @@ static PRBool gUseEnvelopeCmd = PR_FALSE;
 static PRBool gUseLiteralPlus = PR_TRUE;
 static PRBool gExpungeAfterDelete = PR_FALSE;
 static PRBool gCheckDeletedBeforeExpunge = PR_FALSE; //bug 235004
+static PRInt32 gExpungeThreshold = 20;
 static PRInt32 gResponseTimeout = 60;
 static nsCStringArray gCustomDBHeaders;
 
@@ -342,6 +343,7 @@ nsresult nsImapProtocol::GlobalInitialization()
     prefBranch->GetBoolPref("mail.imap.use_literal_plus", &gUseLiteralPlus);
     prefBranch->GetBoolPref("mail.imap.expunge_after_delete", &gExpungeAfterDelete);
     prefBranch->GetBoolPref("mail.imap.check_deleted_before_expunge", &gCheckDeletedBeforeExpunge);
+    prefBranch->GetIntPref("mail.imap.expunge_threshold_number", &gExpungeThreshold);
     prefBranch->GetIntPref("mailnews.tcptimeout", &gResponseTimeout);
     nsCString customDBHeaders;
     prefBranch->GetCharPref("mailnews.customDBHeaders", getter_Copies(customDBHeaders));
@@ -3659,9 +3661,8 @@ void nsImapProtocol::ProcessMailboxUpdate(PRBool handlePossibleUndo)
       // lets see if we should expunge during a full sync of flags.
       if (!DeathSignalReceived()) // only expunge if not reading messages manually and before fetching new
       {
-        // ### TODO read gExpungeThreshhold from prefs. Don't do expunge when we
-        // are lite selecting folder because we could be doing undo
-        if ((m_flagState->GetNumberOfDeletedMessages() >= 20 /* gExpungeThreshold */) &&
+        // Don't do expunge when we are lite selecting folder because we could be doing undo
+        if ((m_flagState->GetNumberOfDeletedMessages() >= gExpungeThreshold) &&
                  !GetShowDeletedMessages() && 
                  m_imapAction != nsIImapUrl::nsImapLiteSelectFolder)
           Expunge();
diff --git a/mozilla/mailnews/mailnews.js b/mozilla/mailnews/mailnews.js
index a06e7ac0fe6..2ef0a66b73f 100644
--- a/mozilla/mailnews/mailnews.js
+++ b/mozilla/mailnews/mailnews.js
@@ -156,6 +156,7 @@ pref("mail.imap.mime_parts_on_demand_threshold", 30000);
 pref("mail.imap.use_literal_plus",          true);
 pref("mail.imap.expunge_after_delete",      false);
 pref("mail.imap.check_deleted_before_expunge", false);
+pref("mail.imap.expunge_threshold_number",  20);
 // if true, we assume that a user access a folder in the other users namespace
 // is acting as a delegate for that folder, and wishes to use the other users
 // identity when acting on messages in other users folders.