Migrating a large amount of emails

[Denis Gomes Franco]

Hey everyone. Any tips on migrating a very large (~28 GB mailbox)?

Here's the thing: my personal email is currently hosted at Zoho. As I'm paying for their premium service, my account has IMAP and POP3 access. I use the Mailsync Cpanel plugin (great plugin by the way) whenever one of my customers want to migrate their mailboxes to my servers.

But the last time I ran Mailsync on a 4 GB mailbox, it took quite some hours for the process to finish. It ran flawlessly but I don't know how long it took as I let it run overnight. I figure that 28 gigabytes would take a day or even more, so I'm looking into speedier solutions.

Zoho lets me download a full ZIP archive of emails (split in parts in case of a large mailbox like mine) but they are in EML format, which as I understand is incompatible with Dovecot.

I think I can WGET these ZIP archives directly into the server so I can download these mails directly to the server without going through my PC first, but what about the file format? And what about messages' timestamps?

Or will I really need to use the plugin and pray for it to not be interrupted mid-operation? :D

 

[FM Kappungal]

Have you tried imapsync by lamiral? Have found it to be pretty fast. Have used it on mailboxes of around 20GB that got over in few hours.

 

[Denis Gomes Franco]

Thanks, I'll check it out!

 

[cPanelMichael]

Hello @Denis Gomes Franco,

You may also find the user-submitted workaround on the following thread helpful:

HOW TO: Using IMAPSync to Transfer mail from server to server

Thank you.

 

[Denis Gomes Franco]

Hey! I just found out that the Mailsync plugin that I'm already using (- Removed -) ships with and uses IMAPSync...

So I'll stay with MailSync, the interface is good enough and really it's very easy to bring emails from other servers.

 

[Denis Gomes Franco]

Quick update for those who will read this thread:
1. I finished migrating my ~28 GB mailbox.
2. Process took about 6 hours. Guess we can say the speed was 4,6 GB per hour, or ~78 MB per minute
3. IMAPSYNC ran just fine on the first try (while migrating other customers sometimes I had to retry 2 or 3 times as it would hang mid-transfer).
4. IMAPSYNC took quite a long time to calculate folder sizes as there were quite a lot of messages there (around 60k).