Not exactly on the Open Source side, but the tool is very open source. It pulls all the emails as .eml files
I had managed to break things royally with my hosted domain and spent much of the weekend dragging IMAP folders around till I discovered this little gem.
Links of Note:
- How can I import mail from one Gmail account to another, preserving my label structure? - Web Applications Stack Exchange
- https://github.com/jay0lee/got-your-back/wiki
The other fun tool of interest is: The Best Free Email Forwarding Service for Custom Domains | Forward Email This lets you have your own domain and use a regular gmail to read receive them. Ie. foobar@mydomain.com and webmin@mydomain.com all goes to myid@gmail.com.
If you’re hosting your own email, then none of this is really relevant, but thought I’d share since this saved me so much time this weekend.