TCB13

Well-Known Member
Jul 25, 2014
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Root Administrator
Hello,

After the upgrade to WHM 11.52.0 (build 5) I noticed a strange thing. My STMP is very very slow. When a email client like Outlook or even RoundCube Webmail tries to send email, it takes about 30s or more for the email to be sent.

What going on? How can I track this issue? What can I do?

Anyway the server load is very low:
cdn.iklive.eu/tcb13/2015/cpanel-server-load-smtp-post.png

Thanks!
 
Last edited by a moderator:

JaredR.

Well-Known Member
Feb 25, 2010
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Since this happened after the 11.52 update, please submit a ticket using the link in my signature so we can take a look at it. You can post the ticket number here so we can follow up.
 

TCB13

Well-Known Member
Jul 25, 2014
62
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As pointed by the support, this issue was caused by having the following option turn on:

- Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam.
The SMTP receiver will wait a few additional seconds for a connection when it detects spam messages in order to reduce inbound spam. The system excludes the following remote hosts from the delay: Neighbor IP addresses in the same netblock, Loopback addresses, Trusted Mail Hosts, Relay Hosts, Backup MX Hosts, Skip SMTP Checks Host, Sender Verify Bypass Hosts, and Greylist Trusted Hosts.
This can be disabled from Home »Service Configuration »Exim Configuration Manager in the basic editor.

Thanks for all!
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,908
2,216
463
Hello :)

This is documented at:

11.52 Release Notes - Delay SMTP transaction for incoming spam

Per the document, this option configures the SMTP receiver to wait a few additional seconds for a connection when it detects spam messages. Disabling the option is likely to increase the amount of SPAM received on your system.

Thank you.
 

Glen Schaefer

Registered
Nov 24, 2015
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SCotts Head, NSW
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Root Administrator
i had exactly the same issue after upgrading to to WHM 11.52.0. I disabled the exim SMTP delay option and everything worked fine. Was getting a 15 sec timeout before that. Am very happy to have found this forum !!! Thank you :)
 

autumnwalker123

Active Member
Jan 19, 2014
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Would this apply to applications on the server sending via SMTP as well? I have noticed a slow SMTP issue via apps like Invision Power Board. Issue is fixed by using external SMTP (e.g. Mandrill).
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,908
2,216
463
Would this apply to applications on the server sending via SMTP as well? I have noticed a slow SMTP issue via apps like Invision Power Board. Issue is fixed by using external SMTP (e.g. Mandrill).
This option is utilized for incoming email. It would not cause slowness for outgoing email. You should open a new thread if you would like us to help you to troubleshoot an issue with outgoing email.

Thank you.