I've got a Windows Server 2008 box where I host a number of websites (on different domains) that send email as part of their functionality.
I've been checking up on the SMTP events and found a number of warnings that look like this:
Message delivery to the host '18.104.22.168' failed while delivering to the remote domain 'orcon.net.nz' for the following reason: An SMTP protocol error occurred. The SMTP verb which caused the error is 'HELO'. The response from the remote server is '550 Invalid HELO/EHLO must contain a FQDN or IPv6 literal in . '.
What does this mean?
I guess it has something to do with my SMTP setup. I'm just using the default SMTP server that comes with Windows.
If it is to do with my setup, is there anything else I should do to setup the SMTP server?
P.s. Is there a better (free) SMTP server I should be looking at? I'm using google apps for email so I don't need to receive emails, just send them.