[Dovecot] Transparent Migration from cyrus to dovecot

[Daniel Parthey]

Hi Jogi

"Jogi Hofmüller" <jogi at mur.at> schrieb:
>One question still remains in my head.  The migration/dsync page [1]
>states that 'The source IMAP/POP3 mailboxes shouldn't be modified while
>dsync is running. Also "dsync backup" means that if the destination has
>any changes that don't exist in source IMAP server, the changes are
>deleted.'  So how does the setup behave *while* I migrate a user's
>mail?

We disabled the login (IMAP, POP3 and SMTP as well) of the user to be migrated and kicked the user from the system. Then we deferred the delivery to the user mailbox in the MTA with a temporary failure and a message like "Mailbox being migrated", with the help of a lookup table in the database. This avoids changes to the affected mailbox during the sync.

If something goes terribly wrong during sync, you can simply switch the proxy back to the old mailbox and re-enable delivery.

No mail will be lost, since it should remain in the remote MTA's mail queue for a while in order to be retried and delivered later.

Regards
Daniel