On 20.6.2013, at 2.24, Antonio Leding tech@leding.net wrote:

Can the above setting be applied on a per user account basis?

I thought that maybe something like per account quotas might be a possible method but not sure.

Nope. Although there's a mail_ prefix, the setting is actually handled by login processes. You can have different values for different protocols (imap, pop3) but not for different users. You could have them for different source/destination IPs/networks though (local {}, remote {} blocks).