[Dovecot] QUOTA Imap Extension

[Brady Wetherington]

Hi - long time lurker, very rare poster

I understand Dovecot's support for mbox quotas is - well, not quite 
there yet. But I actually am not asking about that. I use vpopmail and 
qmail and Maildirs and was wondering about the QUOTA imap extension, 
which allows IMAP clients to query their quota settings.

The reason I need to know about this is that I have a mailserver with a 
chunk of clients and their mail stores are getting large. And starting 
to exhaust my storage. I could just throw more storage at it - but 
they're not paying me for that level of storage, so I need to quota 
them. And my main source of business is one particular consulting 
company, so I pretty much have to do what they say, within reason, and 
they said, "Okay, you can quota everyone, so long as they can at least 
find out what their quota is in Webmail..." Which is pretty reasonable - 
quota'ing people and then not letting them know how close to their quota 
they are seems cruel, especially with the meager IQ's of my particular 
set of clients.

Some research on my part has determined that there's an RFC for a QUOTA 
extension to IMAP, and there are plugins for my webmail program 
(Squirrelmail) which can display the user's quota usage there. Also, 
some mail clients are smart enough to also query the QUOTA extensions 
and let the user know how close they are to their max quota usage.

I'm also planning a pretty decent-sized technology transition in the 
near future (switching to a shared-storage system with two servers, etc, 
etc), and I could be convinced to perhaps try and change my quotaing 
system at the same time - for instance, switching to filesystem quotas 
instead of vpopmail quotas, if that will help.

The scary possibility that I guess I have to prepare myself for is that 
dovecot Just Doesn't Do It, and I need to figure out some other way of 
informing the clients of their quota usage - possibly a script that goes 
and recurses through maildirs and sends little emails if users are at a 
certain percentage of their actual usage, or something...I'm certainly 
not looking forward to writing that, but it's not a fate worse than death...