[asoplata]

I recommend using isync (aka mbsync) https://isync.sourceforge.io/ to download an offline, IMAP-style copy of your email; it seems to be faster than offlineimap http://www.offlineimap.org/ which does the same thing. Many people have it run on a simple cron job. You can then use Thunderbird etc. on your full local copy of the mailbox.

[nfriedly]

Thank you, I'll try that out!