How to make SMTP sending of email faster?

[Mateo1041]

Hi,

Sending email has been slower than we feel it should be. On average it takes anywhere from 5-10 seconds for an email to send. I've already added the -Rt0 option and my smtp_psa file looks like this:

service smtp
{
        socket_type     = stream
        protocol        = tcp
        wait            = no
        disable         = no
        user            = root
        instances       = UNLIMITED
        server          = /var/qmail/bin/tcp-env
        server_args     = -Rt0 /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true
}

Any ideas on how to make this faster? Any help would really be appreciated. Thanks!

- Matt.

 

[wagnerch]

You might want to be a bit more specific, are you referring to:

a) inbound mail and/or relay mail via client
b) mail originating from the server


Keep in mind that SpamAssassin is enabled, and that adds 4~8 seconds overhead depending on the size of the messages, number of concurrent requests, load of the server, planet alignment, etc.

 

[Mateo1041]

I'm talking about when sending SMTP email from a client like Thunderbird.

Can I disable scanning of outgoing email with SpamAssassin? I only need to scan incoming email.

Thanks,
- Matt.

 

[wagnerch]

I don't believe the scenario you are talking about would be affected by SpamAssassin. SpamAssassin really gets involved in the delivery phase (via the .qmail file in each recipient's mail directory under /var/qmail/mailnames).

 

[wagnerch]

Have you confirmed where the delay is? I am assuming you are thinking it is DNS related, because you added '-Rt0'.

It should be noted that not only does tcp-env do DNS lookups, but so does rblsmtpd. I would validate the performance of the RBL servers using dig(1) and I would also validate the performance of your DNS servers (look in /etc/resolv.conf).

You can also get the pid of your xinetd process and do the following:

strace -p<xinetd pid> -o /tmp/xinetd_strace -f -ff -tt -T

At the beginning of each line you will see a timestamp, and at the end of each line you will see the time spent in the call.