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

[Tim Smith]

My next guess was the upstream data rate. My router states that the 
upstream is 10x slower than downstream so I guess this is the culprit. 
Time to move to a VPS methinks...

On 24/08/12 13:50, Stan Hoeppner wrote:
> 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.
>