~R is read messages
~N is unread
l~N limit to only unread messages.
T~R will tag all read messages
T~N will select all unread messages
T ~d>30d will tag all messages older than 30days
T ~d 1/1/11-31/12/11 will tag all messages from 2011 year
l~d<1d all messages from today

mutt patterns: http://www.mutt.org/doc/manual/manual-4.html#ss4.2

How do I save/delete/copy/print/pipe multiple messages?

The keywords to look for in the manual.txt and the "?"-run-time help are:


Tag the messages you want to operate on, using t (tag-entry) or T (tag-pattern). Then, issue the tag-prefix command (default ;) followed by whichever operation you want. For instance, with default keybindings, ;s+archive would save all tagged messages to the +archive folder.