A bank we're working together is trying to send us an auto generated email to our company's email but it keeps bouncing off with the following SMPT error:
Status: 5.5.0
Diagnostic-Code: smtp;550 Access denied – Invalid HELO name (See RFC2821
4.1.1.1)
Since I'm also not a sysadmin of my company, I can't tell if the problem is from the banking side or our mail server side.
Could anyone suggest here what could be the problem? Such if if any changes need to be done on my email server. I only have access to the cPanel of my company's hosting.
Best Answer
according to the error message the sending server doesn't use a fully qualified domain name in the smtp HELO, so for example instead of heloing with "servername.example.com" it maybe just helos with "servername" (check your server log for the actual values) This behaviour is blocked by many receiving MTAs.
The sender should fix the HELO.