Migrating email IMAP to IMAP
We have a customer very unhappy with his current service provider. He has recently moved mail from POP to IMAP and wanted to move elsewhere for mail. I told him of the positive experience I've had with Google Apps. He is a power user and has 20GB of mail to move. My job was to move the mail from one mail provider to another over a weekend.
Outlook doesn't cut it (see posts passim) and silently drops mail even though it reaches 100% completion with no errors. I could have used Google's plugin for Outlook, but this would have taken forever. I only had a weekend as the customer wanted to be fully migrated by Monday so he could tell his existing provider where they could put their customer service.
I had a look around and discovered offlineimap. It can do IMAP to local disk, local disk to IMAP, IMAP to IMAP and even has a Gmail option.
Sadly, I discovered that the Gmail option is a read-only affair. You cannot use offlineimap to backup to import into a Gmail account. However, you can tell offlineimap to write to an IMAP account. I therefore chose to run it in IMAP<->IMAP mode. This is how I migrated my customer:
#apt-get install offlineimap
[general] accounts = MigrateBobbinsToGmail socktimeout = 600 # Gmail max attachment size maxsize = 25000000 [Account MigrateBobbinsToGmail] localrepository = Gmail remoterepository = Bobbins [Repository Gmail] type = IMAP remotehost = imap.gmail.com remoteport = 993 remoteuser = email@example.com remotepass = password ssl = yes [Repository Bobbins] type = IMAP
# We don't want any mail/folder structure to be copied back to here. readonly = True remotehost = imap.bobbinsprovider.foo remoteuser = firstname.lastname@example.org remotepass = password
Save the file. Make sure the number to trim any emails which are >25MB big on the bobbinsprovider.foo server and then run. If you have big attachments, you are going to end up with errors importing into Gmail and offlineimap will stop.
$ offlineimap -u blinkenlights
This is just one example of how offlineimap can be used, but it is a very flexible swiss-army IMAP tool.