It wouldn't be impossible to iterate over a series of mails, and get the message-bodies, but it would be a bit fiddly and annoying as the program was more designed as an email-client.

https://github.com/lumail/lumail/

https://lumail.org/

Honestly I'd probably write something in perl/go/similar to just walk over a remote IMAP mailbox:

* Search for messages that are unread, or which don't have a given tag.

* Process each one.

* Mark as read, or add a tag.

(I actually did something like that recently for processing DMARC reports.)