[Dbmail] Massive, massive mailboxes?

[Chris Nolan]

Hi all!

I am going to migrate a Cyrus IMAP setup to DBMail (I hope) and have but 
one main concern. Does anyone know how DBMail will handle a mail store 
where each user has between 1 GB - 4.3 GB of stuff stored in their 
mailbox (including subfolders etc). That's the amount that's being 
stored with Cyrus at the moment.

Given the above consideration, would anyone recommend MySQL or Postgres 
over the other and, if so, which version (MySQL 3.32 vs MySQL 4.x etc).

Thanks!

Chris