Cpanel/WHM 421 Too many concurrent SMTP connections

MindServer

Well-Known Member
Mar 18, 2020
189
30
28
Spain
cPanel Access Level
Root Administrator
Hi,

The services exim, clamd and spamd were down and we restarted him.

All restart good (appear success message), but now cannot send emails. When i connect since webmail or since thunderbird SMPT not working.

Can you tell me how solve him?. I used this commands for restart services:

Code:
/scripts/restartsrv_exim

/usr/local/cpanel/scripts/restartsrv_clamd

/scripts/restartsrv_spamd – status
Now, when we want to connect with SMTP returned me this error: 421 Too many concurrent SMTP connections

I don't know why because we only have 1 email in this server (all dedicated server) and connect from 2 PCs. We checked and exim limit is in 30 connections.

Thank you very much.
 

MindServer

Well-Known Member
Mar 18, 2020
189
30
28
Spain
cPanel Access Level
Root Administrator
How I can check or close all SMTP connections?. We are not connected to this emails, this isn't normal.

Too I receive constantly messages with warning:

FAILED: spamd
FAILED: exim
HANG: chkservd

Thank you very much.
 
Last edited:

cPanelLauren

Product Owner
Staff member
Nov 14, 2017
13,295
1,255
313
Houston
Hello,

Now, when we want to connect with SMTP returned me this error: 421 Too many concurrent SMTP connections

This simply indicates that too many people are connected at once. This number defaults to 100 on cPanel servers, not 30 the smtp_accept_queue_per_connection setting is 30 by cPanel's defaults but this is completely different and related to the number of delivery processes exim will automatically start.

Before you make any modifications I'd suggest evaluating whether or not these are valid connections. You can change the number of concurrent SMTP connections allowed on the server at once by going to WHM>>Service Configuration>>Exim Configuration Manager -> Advanced Editor -> smtp_accept_max

For the services failing, the fact that they're all related to mail along with the issues you're having with SMTP connections is concerning.

What's in the mailqueue right now (# of emails)?
Code:
exim -bpc
The exim logs will also detail connections as well as every mail transaction occurring on the server here:
Code:
/var/log/exim_mainlog