Migrating emails

A few days back I decided to change my mail provider from Gmail to a local (German) one. Naturally I wanted to take my old mail with me.

There are a few online migration tools like ShuttleCloud or Audriga but in order to copy the emails from one mailbox to another they all need the necessary passwords. So that’s out of the question!

One of the many command line tools to migrate emails is OfflineImap. Normally it is used to copy mail from a remote IMAP server into a local mailbox but it can also copy those mails into a remote one.

OfflineImap should be in the package repository of your linux distribution so the installation shouldn’t be a problem. Otherwise the documentation is pretty good. After that you can cp an example config file from /usr/share/offlineimap/offlineimap.conf to ~/.offlineimaprc and edit it based on the extensive comments. When you are done just run offlineimap and wait … if you have many mails, wait for a long time.

The config file I used to migrate my mails from Gmail to the new provider is shown below. There are a few specialities:

  • No passwords: One has to provide them at start.
  • Server fingerprints are stored in the config file: When you run offlineimap it will tell you that it doesn’t know the server and show you its fingerprint. Verify and add it to the config file.
  • Don’t touch Gmail: readonly=True
  • Blinkenlights UI: Nice ASCII art
metadata = ~/.offlineimap
accounts = main
ui = Blinkenlights

[Account main]
localrepository = <new-provider>
remoterepository = Gmail
status_backend = sqlite

[Repository <new-provider]
type = IMAP
remotehost = <new-provider-host>
remoteport = 993
remoteuser = <new-provider-user>
ssl = yes
cert_fingerprint = c1d95bad26e8473892c4f75aba3f9f226205479b

[Repository Gmail]
type = Gmail
remoteuser = <gmail-user>
readonly = True
cert_fingerprint = 89091347184d41768bfc0da9fad94bfe882dd358
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