SpamAssassin Outgoing Scan Causing Slow SMTP?

[uk01]

Hi we enabled the exim option to scan outgoing mail with spam assassin.
However, I've just become aware this has introduced a delay of about 6-8 seconds when sending email.

This delay does not affect Outlook/Mac mail users as it goes to outbox but in some mail clients or webmail apps it sits saying "sending" for 6-8 seconds.

Is there any way of speeding this up?

Outgoing messages are not scanned as default, is this because it's not really required?

 

[cPanelLauren]

The only instance in which I would anticipate a delay like this would be if the mail server was extremely busy. In that instance scanning of outbound mail would cause some additional delay. There really aren't any modifications you can make to the outbound scanner to speed this up, short of disabling the scanning, unfortunately.

Thanks!

 

[uk01]

Thanks for your reply, server load is low as we keep a small amount of accounts per vm.
However, I can confirm turning the option off allows the email to send instantly.

I also discovered, if I remove any urls from the email, such as in the signature, it sends instantly, so it's Spam Assassin slow at scanning urls for spam.

 

[cPanelLauren]

Hi @uk01

That's interesting, are you running bind? If so what is the output of the following:

cat /etc/resolv.conf

 

[uk01]

Sorry about the slow reply, I've been away.

That command gives us the 3 DNS servers supplied by our datacentre.

 

[cPanelLauren]

HI @uk01

Do they allow you to use public resolvers such as googles? I am curious if there is an issue with one of the DNS resolvers they've provided. If they do allow you to use different resolvers can you replace the entries in the resolv.conf with different ones such as Google's? For reference they're:

8.8.8.8
8.8.4.4

 

[uk01]

Thanks, I think we can use any so I'll try google or the new cloudfare public dns.

 

[cPanelLauren]

HI @uk01

Yea the new CloudFlare DNS resolvers are supposed to be faster too though I haven't done a lot of testing personally, definitely worth trying out. Please let me know if the issue persists after changing over.

Thanks!

 

[uk01]

Early tests but this does seem to have made it faster.
I did have an issue with network services overwriting the dns though - for anyone else reading this you need to remove DNS1, DNS2, etc from /etc/sysconfig/networkscripts/ifcfg-* to stop network manager taking control. Then change the ip's in resolv

Thanks @cPanelLauren for your help

 

[cPanelLauren]

Hi @uk01

I just want to point out that you shouldn't have to do this because you shouldn't actually be running Network Manager, it's not supported by cPanel and can cause issues with ipaliasing. We have instructions on how to disable it here: How to Disable Network Manager - cPanel Knowledge Base - cPanel Documentation

All you should have needed to do (without NM) is modify /etc/resolv.conf

Thanks!

 

[uk01]

Thanks, I'll check this on our newest server. I remember disabling it a while back on all the other servers. It must be active for some reason on the latest set up.

 

[cPanelLauren]

Hi @uk01


Either way, I'm happy to hear that modifying the resolvers has made this function as intended!

 

[Kurieuo]

I too just noticed mail sending slow. I'm not sure when it started, but I hadn't noticed how slow it was until recently via form submits that deal with email (this is a new server been running almost 6 months now). It's not just taking 8 seconds though, but like 20-30 seconds via webmail. I'm using Google's resolvers.

/var ran out of disk space on the applicable server, and I'm not sure if that's related, but I think that aligns with about the same time I noticed delays happening i.e., with WHMCS email sending admin tasks.

In any case, I went through Exims settings bit by bit, and not until disabling the SpamAssassin scanning on sent emails did emails send instantly! My next step was to search here on that setting slowing email down, and I came across this thread.

Obviously, be great to have SA scanning outgoing mail though. I'm not sure if running out of space on /var is a red herring, but thought I'd mention it anyway.

Any other ideas on what I might try? Server isn't under any real load, the mail queue is empty, so it really should be quicker.

 

[cPanelLauren]

Hi @Kurieuo


When SpamAssassin for outgoing mail is enabled do you see anything indicative of an issue in

/var/log/maillog

or

/usr/local/cpanel/logs/error_log

Thanks!