limit can also actually search inside messages, depending on the search patterns you give. From the Patterns subsection of the Mutt reference:
~b EXPR messages which contain EXPR in the message body
~B EXPR messages which contain EXPR in the whole message
~b only searches in the body, whereas
~B also searches in the headers.
Note that this can be quite slow, since it may have to download each message one by one if they are not already cached. If you have a mutt version greater or equal to 1.5.12, you can cache the ones you are downloading for later use by setting
message_cachedir to a directory where you want to store message bodies, which can significantly speed up searching them (and the same for headers with