[Dovecot] Size of Mailbox affecting the sending of mail?

[Timo Sirainen]

On 24.8.2012, at 13.53, Tim Smith wrote:

> Having set up my mail server (Dovecot/Postfix), users are experiencing long delays (a couple of minutes) when sending mail from mail client such as Thunderbird - this increases with attachments. Having had a brief discussion with someone, they mentioned that the reason that this may be to do with the size of the mailbox. I couldn't see the rationale behind this unless Dovecot is syncing the mailbox after every sent mail (due to possibly saving the sent item?) The mail is being delivered successfully but the amount of time it is taking to complete the action is far too long!

Other than the bandwidth others already mentioned, the only reason it could be Dovecot's fault is exactly the size of the Sent mailbox. How large is that and what mailbox format are you using?