imapbackup VS offlineimap3

In terms of backup you could do incremental backups, example here in python - not tested by me personally but seems good.

If you want it totally DIY https://github.com/rcarmo/imapbackup and then any flat text search.

Check this out, you can use it with bridge https://github.com/rcarmo/imapbackup

If you have access to the server you could make backups on that end (that is what we where doing) if you dont have access to the server you would need to login to each mailbox to create the backup i suppose. Dont know which tools are good for that but i found this one it might help: https://github.com/rcarmo/imapbackup

There are loads of imap backup options from a quick search, such as https://github.com/rcarmo/imapbackup

I suspect your new mail server supports IMAP. So you can run offlineimap to "sync" mails from Proton Mail to your server, as long as you have Proton Mail Bridge available.

I have also configured it that no deletes are synced, so I don't loose anything I delete by accident (sync_deletes). Also set the folderfilter to your liking. For all options check out https://github.com/OfflineIMAP/offlineimap3/blob/master/offlineimap.conf

Offlineimap can backup Gmail without problems, including the labels (they are added as X-Keywords header to the mail).

You can synchronize your email off gmail using offlineimap or any other similar program (you can and also should make a full request of your data with Google right now, because even an unmanaged dump can serve as a backup copy). You could then ensure you lose nothing by version-controlling the resulting maildir using git.

Part of this is due to bad software design. The email server provides a service, but nothing prevents you from backing up the emails you synchronize... except for software that doesn't allow it because the devs didn't give a shit.

So I have to ask, why JMAP? And does anything like offlineJMAP exist?

i can not longer use mu4e with my outlook account because of 2FA. I used to set it up through a combo of DavMail and offlineimap3, but now that doesn't work because DavMail can no longer create a bridge between outlook and imap, since I don' know how to get it working with 2FA.

On https://www.offlineimap.org there is still a link to the repository that uses Python 2 which is no longer supported. At https://github.com/OfflineIMAP/offlineimap3, development apparently continues with Python 3. There is version 8.0.0 available (https://github.com/OfflineIMAP/offlineimap3/releases/tag/v8.0.0)