Migrating emails from one server to another using imap

I recently switched the email hosting from one provider to another. I always set email up as IMAP so the mail is stored and can be accessed and synchronised on multiple devices. This ‘How to’ is based on you having a similar setup. There are tools out there that perform this task automatically but being a control freak I wanted to do this manually to ensure all went well.


  • You have an IMAP mail account on one server, and you want to migrate this account and the messages to another server.
  • The old server is still up and running and the nameservers still point to the existing hosting (e.g. the server you are migrating the messages from)
  1. Create a mail account with the new provider that exactly mirrors settings of the existing account on the old provider e.g. same user, same password, same email address
  2. Install an additional email client on your desktop system – I recommend a separate client from your main client in case it all goes awry. I’ve successfully tested it with the same client when using Thunderbird 3 but ymmv.
  3. Set up the old mail account in thunderbird  (the provider you’re migrating from)
  4. Important: Ensure the account is setup as IMAP in Thunderbird
  5. Deselect any default junk mail options (This stops Thunderbird  from automatically moving mails to different mail boxes)
  6. Let Thunderbird connect to the old mail account and download all emails
  7. Set up the new mail account in thunderbird (the provider you’re migrating to) – You will need to use the ip address of the new server as the imap and smtp dns names aren’t pointing to the new provider yet
  8. Once Thunderbirds has connected and and set up the inbox you will need to create the folder in the new mail account, mirroring the folders in the old account on the old servers
  9. In the OLD Mail account (the one you are migrating from), select each mail folder, CTRL+A to select all the messages, right click and choose ‘Copy to…’ and select the equivalent folder on the NEW server version of the account
  10. Repeat step 9 for all folders/messages in the account (don’t forget the Sent items!)

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