If you are trying to configure SMTP mail transport using PHPMailer or other third party scripts, you might encounter this error
SMTP -> FROM SERVER:220-server.yourserver.com ESMTP Exim 4.80.1 #2 Thu, 05 Sep 2013 14:23:57 -0400 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail. SMTP -> FROM SERVER: 250-server.yourserver.com Hello server.yourserver.com [188.8.131.52] 250-SIZE 52428800 250-8BITMIME 250-PIPELINING 250-AUTH PLAIN LOGIN 250 HELP SMTP -> ERROR: Password not accepted from server: 535 Incorrect authentication data SMTP -> FROM SERVER:250 Reset OK
To fix this issue, you will need to login to your WHM account as root. If you do not have this access, contact your hosting provider for instructions and assistance.
Navigate to Home »Server Configuration »Tweak Settings
Adjust the following parameters:
Restrict outgoing SMTP to root, exim, and mailman (FKA SMTP Tweak) - Off
Prevent “nobody” from sending mail - On
Allow users to relay mail if they use an IP address through which someone has validated an IMAP or POP3 login within the last hour (Pop-before-SMTP) - On
Add X-PopBeforeSMTP header for mail sent via POP-before-SMTP - On
Save your settings. This will reload the mail server and you should be all set!