diff --git a/mozilla/mailnews/base/resources/locale/en-US/messenger.properties b/mozilla/mailnews/base/resources/locale/en-US/messenger.properties
index c645a8676e2..5a4d8f7d846 100644
--- a/mozilla/mailnews/base/resources/locale/en-US/messenger.properties
+++ b/mozilla/mailnews/base/resources/locale/en-US/messenger.properties
@@ -76,6 +76,9 @@ serverType-movemail=Unix Movemail
 recipientColumnHeader=Recipient
 senderColumnHeader=Sender
 
+sizeColumnHeader=Size
+linesColumnHeader=Lines
+
 # status feedback stuff
 documentDonePrefix=Document: Done (
 documentDonePostfix=secs)
diff --git a/mozilla/mailnews/base/resources/locale/en-US/threadpane.dtd b/mozilla/mailnews/base/resources/locale/en-US/threadpane.dtd
index 2fa5afc54db..c543441d8fe 100644
--- a/mozilla/mailnews/base/resources/locale/en-US/threadpane.dtd
+++ b/mozilla/mailnews/base/resources/locale/en-US/threadpane.dtd
@@ -25,6 +25,7 @@ Rights Reserved.
 <!ENTITY priorityColumn.label "Priority">
 <!ENTITY statusColumn.label "Status">
 <!ENTITY sizeColumn.label "Size">
+<!ENTITY linesColumn.label "Lines">
 <!ENTITY unreadColumn.label "Unread">
 <!ENTITY totalColumn.label "Total">
 <!ENTITY orderReceivedColumn.label "Order Received">