How to resolve “550 Access denied – Invalid HELO name” error from Outlook (0x800ccc78), Windows Mail, etc in cPanel/WHM Exim mail servers
At Bobcares website support services, this is a common error we see in cPanel/WHM shared hosting servers. We’ve seen that strict anti-spam rules or lack of SMTP authentication usually cause this error.
The mail user reports the error:
Task firstname.lastname@example.org – Sending reported error (0x800CCC78): ‘Cannot send the message. Verify the email address in your account properties. The server responded: 550 Access denied – Invalid HELO name (See RFC2821 126.96.36.199)
Corresponding entry in Exim logs say:
2014-09-24 07:06:31 H=isp-ip-dom.net [xxx.xxx.xxx.xxx] rejected MAIL <email@example.com>: Access denied - Invalid HELO name (See RFC2821 188.8.131.52) (more…)