Wow. We never should have switched from UW-IMAP to Dovecot. Having a 750,000 user base. We made the switch to Dovecot in an effort to trim a little overhead on our systems. But our OS (FreeBSD 5.4 - UFS) version is rapidly reaching EOL. All future versions will default to UFS2.
Curious, seeing as I'm working on a large mail system atm. Why are you using FS quota's? Having been awhile since I used FS quota's, it is my understanding, that each user that has a FS quota, must be on the system as a 'real' user. With that many users, I would expect that you would have some sort of user backend (LDAP, SQL...) and they would be 'virtual' to the system.
Regardless of if they are virtual, or 'real' users, why not use the dovecot Maildir++ Quota's? They work, regardless of FS, are supported be a number of MTA's as well, and "Just Work". Do you REALLY need FS quota's for emails? I'm just trying to understand why you need FS quotas.
Tim
Linux Counter user #273956