I have a linux server but seem to get too many smtp connections at once.

[chaze]

Do you know how I can see who is connecting so much to my smtp so much? It's centos 4.5 linux host dwhs and it runs cpanel

Here is the error:

421 Too many concurrent SMTP connections; please try again later

[DimaYasny]

/var/log/mail or whatever logging path your MTA uses

[Darkflib]

iptstate might also be able to point you to the culprit.

Iptstate allows you to look at the iptables connection tracking table and see what connections are currently being seen by iptables.

You must have the iptables conn_track module installed to use it, which is pretty common.