Migrate IMAP account between providers - client access only

I have an IMAP E-Mail account with my old provider.

I have a new, empty IMAP account with the new provider.

Is there a tool or Thunderbird to migrate the E-Mail data from one account to another? I'm a bit wary about just doing a drag & drop in Thunderbird because it's quite a lot of data, and I have a deep distrust against how Thunderbird deals with IMAP data.

I'm working on Windows 7, so I would prefer a graphical Windows tool. If need be, I can work from a Linux box as well.

From serverfault Pekka

• Try using imapsync

  Pekka : Cheers sntg, but I'm on Windows with this. Sorry, should have mentioned it - adding it now.

  ErikA : Imapsync is great - well worth spinning up a linux box if you can.

  Dan Andreatta : imapsync is written in Perl. Should run run in Windows as well.
  From sntg

• I'd recommend the drag and drop, but do it in manageable chunks, e.g. 1 month at a time. You could also copy down to a local directory first, then up to the new server.

  Good luck,

  --jed

  From Jed Daniels

• Be carefull when draging and dropping IMAP to check the contents of any subfolders. Different flavours of IMAP handle subfolders differently and with some thuderbird will transfer the folder but not its contents. I've found the best mail client for draging to/from Courier IMAP accounts to be Mulberry. http://www.mulberrymail.com/ - Its a bit retro but does the job.

  If you end up using a syncing tool, you run the risk of ending up with duplicates. In that case there is a Thunderbird plugin that will remove them for you but it can gag on large inboxes. https://addons.mozilla.org/en-US/thunderbird/addon/956

  From ChrisRyan

• Like sntg, I'd try using imapsync first (should also run under Windows with ActivePerl).

  If you can't get it to run, try imapsize which can - besides a lot of other things - migrate your mails between two IMAP accounts.

  From joschi