www.naumann.cc

I moved my email account to FastMail.fm and had to migrate an imap mailbox via my ubuntu desktop. If you want to join them feel free to use my link with referal code FastMail.fm

First we have to install the imapsync package:

sudo apt-get install imapsync

Then we have to trigger the migration:

imapsync --syncinternaldates \
  --host1 mail.source.tld --authmech1 LOGIN --user1 user@domain.tld --password1 secret \
  --host2 mail.target.tld --authmech2 LOGIN --user2 user@domain.tld --password2 secret

Now drink a coffee , because this can take a while.