The attached patch allows to link directly to a message through the frameset, so that the folder list on the left hand side will be displayed:
http://localhost/squirrelmail/src/webmail.php?right_frame=read_body.php&mailbox=INBOX&passed_id=3391
Use Case: An email portlet in a portal that displays just a list of recent emails. Each entry links to the full email body. But without this patch the left hand navigation is missing.
message_links_through_frameset.patch