Suddenly getting "R=send_to_smart_host T=remote_smtp defer (110): Connection timed out"

jndawson

Well-Known Member
Aug 27, 2014
289
31
78
Western US
cPanel Access Level
DataCenter Provider
We have 3 cPanel boxes (let's call them 1,2 and 3, all running WHM 11.48.0 (build 7)) sending email to our smarthost, which is actually 2 mailfoundry devices.

We had made a couple of tightening adjustments on #2 after a large corporate customer had several email accounts hacked and thousands of spam email were sent out. Most were stopped by our foundry boxes, so relatively minimal impact. Everything continued as normal for several days.

All three cP boxes have been running nicely for several weeks, mail alternating between our smarthosts. Suddenly, this morning, one cPanel box (#2) suddenly started stacking up email. Both #1 & #3 continue to run just fine. Investigation on #2 showed numerous entries:

"R=send_to_smart_host T=remote_smtp defer (110): Connection timed out"

No outgoing mail, but incoming continued to flow.

Telnet to each smarthost from #2 fails - indicates a network issue.

But! Suddenly the queue will run and a bunch of the queue gets properly sent. But then, it stops and we go back to the timeout issue. And the queue never empties - always several hundred emails - manual agitation does nothing.

The occurrence is entirely random. I've stopped Exim, removed the /var/spool/exim/db/retry* and~/misc files as was recommended on the Exim forum, and double-checked anything having to do with mail and ports and sending and waiting and you name it.

I have looked all over the place for an answer to this. I've even turned off both cphulk and the firewall and tested, and the same thing happens.

Any ideas?
 
Last edited:

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,910
2,215
363
Hello :)

It sounds like a network/firewall issue. Have you checked with your data center to verify traffic isn't restricted from the network or router level?

Thank you.
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,910
2,215
363
Feel free to open a support ticket using the link in my signature if you want us to verify it's not an issue with cPanel or Exim. You can post the ticket number here so we can update this thread with the outcome.

Thank you.