Please turn on SMTP Authentication in your mail client


Sep 24, 2012
cPanel Access Level
Root Administrator
Hi, we have a WHM / cPanel server that has about 60 clients on it and over the past several months we noticed that some people are reporting problems with people e-mailing them and that the external people get message like the following: gave this error:
Please turn on SMTP Authentication in your mail client, or login to the IMAP/POP3 server before sending your message.[ip address]:3424 is not permitted to relay through this server without authentication.

This occurs when someone tries to email one of our customers that is set-up on our server. I have looked into this and not really found anything concrete that has helped other than the obvious that the external users don't have there programs set-up properly but as this is happening more regularly it seems I was wandering if it could there be something on our server that is not as it should be?