Search for mail content with Mutt

search and 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 STRING       If IMAP is enabled, like ~b but searches for STRING on the server, rather than downloading each message and searching it locally.
~B EXPR         messages which contain EXPR in the whole message
=B STRING       If IMAP is enabled, like ~B but searches for STRING on the server, rather than downloading each message and searching it locally.

That is, ~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 header_cache).

You can add flags to the search command, to search the body use the search function with the ~b modifier. So to search for cheesecake inside your mail bodies:

/~b cheesecake

Put ~b in front of your search pattern to search only in the body of mails. For searching additionally in the headers, use ~B

There are plenty of other patterns described in the mutt manual.