How to parse email notifications?

Question

Email Marketing

There is a site with sending notifications to the mail of users. As usual, among the database of email addresses there are a lot of dead people (mostly from mail.ru, be it wrong). As a result, tons of notifications about non-delivery of letters come to the mail.
Task: parse all these letters (Gmail box) and tear out all the mentioned mailboxes from there in order to unsubscribe them from the mailing list on your own.
Please share your thoughts. I don’t even know how to merge these notifications from Gmail in a human-readable form.

Answer 1

It is for mail.ru that you should use their Postmaster.mail.ru service for tracking mailings from your domain. There you can confirm ownership of the domain from which the mailings are sent and set up FBL (feedback loop) .
And with GMail, we parsed the spacing with a php script that picked up mail only with certain tags that were assigned by GMail filters, the script erased the processed letters.

Answer 2

Maybe a simple pop3 client in php?