On 8/24/2012 5:53 AM, Tim Smith wrote:
Hay Tim,
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!
You probably have multiple factors involved in this mail sending delay issue.
One may be that you're not bypassing your Postfix restrictions on your submission service. To fix this, disable your restrictions in the master.cf service definition of your submission service. For example:
587 inet n - n - - smtpd
-o smtpd_enforce_tls=yes
-o smtpd_sasl_auth_enable=yes
-o content_filter=
-o smtpd_client_restrictions=
-o smtpd_helo_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,
permit_sasl_authenticated,reject
-o receive_override_options=no_unknown_recipient_checks,
no_address_mappings,no_header_body_checks
This should squash any/all delays in Postfix submission.
Another is the fact you're storing the users' Sent folders on the IMAP server. Typically there's nothing wrong with this. I do this and I see zero delay in Tbird. If a good portion of the delay you're seeing is Tbird copying messages to the Sent folder then I'd say you may have a duplex mismatch or some other network layer issue.
What is the network topology between these client MUAs and the server? Full duplex fast ethernet? GbE? Or is the server at a remote location, say a colo/VPS server, and your clients are submitting over a shared ADSL/cable circuit to the server? If this is the case you'll always have substantial delays as the real outbound transmission rate of the best ADSL/cable circuits is only 500-1000 Kbps. Sending an attachment over such a pipe is always going to be slow, doubly so if you're copying to an IMAP Sent folder over the same connection, plus sharing it for web browsing, etc, amongst many users.
If this is a SOHO environment with shared ADSL/cable the server needs to be on site, with clients connected via ethernet. This will allow instantaneous submission and Sent copying, while pushing the delay to the Postfix outbound queue, where it's invisible to your users.
-- Stan