Hi All!
I am working on a complete migration from an old solaris machine running Cyrus IMAP v2.3.14 and wish to migrate all users to a new ubuntu vm running Dovecot 2.0.19.
What I have so far is a fully functional dovecot installation with LDAP / Dovecot SASL auth using Maildir++.
My plan is to use Perdition IMAP proxy on a third host and migrate users a few at a time (see attached picture of my whiteboard).
The proxy is in place and already used by webmail clients to connect to the old server, shortly I will change the dns to point smtp.domain.com and imap.domain.com etc to the proxy instead of the old server but I haven't finished testing yet. Once that is done it is a simple matter of changing the proxy configuration per user to make them hit the new server instead.
The problem I am having with this is that I am using Imapsync (http://imapsync.lamiral.info) to perform the initial synchronization (i have scripted it to maintain sync every 10 minutes with the addtion of "--maxage 1" option) using the following command line options:
/usr/local/bin/imapsync --noreleasecheck --useheader ALL --delete2 --expunge2 --tmpdir /var/vmail/cache --subscribe --subscribed --tls1 --tls2 --usecache --nofoldersizes --nocheckmessageexists --host1 oldserver.domain.com --authuser1 adminuser --user1 testuser@domain.com --authmech1 PLAIN --password1 <HIDDEN> --host2 newserver.domain.com --authuser2 adminuser --user2 testuser@domain.com --authmech2 PLAIN --password2 <HIDDEN>
All email is copied over and stored in dovecot as you would expect. Then I switch the user to the new server on the imapproxy and restart the client (thunderbird or whatever). This is where all email headers are downloaded again as if they were new! There are *Many* users here who would complain intensely if this happened and I was really wanting the migration to be as invisible as possible.
Is there a way to do what I have described without the clients redownloading headers / full messages?
I have been working on this for some time now but have hit a roadblock and don't know where to turn, any help would be really appreciated!
Notes:
- The proxy is not used during imapsync.
- Some users have 20 years worth of mail running into 10's of GB
- I have looked at dsync but the docs state that the mailbox should not be accessed during sync, this is not possible for me (it doesn't say why this is the case however)