This check says that the RFC requires a fully qualified hostname for HELO. Most internet searches show this to be a "safe" check that shouldn't really kill any real mail. Lately, noticed no ebay mail was coming through, looked through the logs and see entires like:
Nov 9 20:30:58 host2 postfix/smtpd[16167]: NOQUEUE: reject: RCPT from mxpool19.ebay.com[66.135.197.25]: 504 5.5.2 <mx88>: Helo command rejected: need fully-qualified hostname; from=<e...@ebay.com> to=<m...@hiddendomain.com> proto=ESMTP helo=<mx88> mx88 is of course not a FQDN. So, it was correctly rejected per the setting. Obviously, I can try and whitelist all the ebay servers, but, it's a slight pain. Could be a moving target, etc. This would allow me to keep the setting, but.... Since this did block mail from a rather well known common mailer, I am starting to wonder how safe this check really is. Perhaps it's not so safe. Yes, that is a configuration error on ebays part, but, I don't think you really want to block ebay mail. Are you finding this is not as safe a check as it should be, since presumably the RFC requires it, still, people make mistakes? Is it really of much use these days anyway for blocking spam?
