... for anyone out there struggling, WELL WORTH GETTING A SUPPORT TICKET. Response was very quick and Zhang logged in and fixed the issue in a matter of a few seconds, literally saving me hours of work. Very happy with the support on this.
Upgrade an existing iRedMail server to the new release immediately follow it. For example, if you're running iRedMail-0.9.0, this upgrade service will upgrade it to iRedMail-0.9.1, not the latest iRedMail-0.9.9. You can find iRedMail version number in file /etc/iredmail-release.
Upgrading iRedMail doesn't install new components shipped in new iRedMail release.
If you have any customization for Roundcube webmail or other softwares, you have to sync the customizations yourself and manually after upgrading.
If you own a valid iRedAdmin-Pro license, we will upgrade the iRedAdmin-Pro software to the latest stable release too.
I ordered remote upgrade support ... Everything worked so smoothly, that there was no service interruption, no angry users and not a single mail lost. Thanks again, it was well worth the money!
Microsoft Exchange (cannot migrate user passwords)
Old iRedMail server or Linux/BSD based mail server
Standard IMAP server like Dovecot, Cyrus-IMAP
Depends on the number of mail domains/users/aliases, mailbox size, and other data needed to be migrated, the price may be different, there isn't a fixed price for migration service.