HELO
December 5, 2007
After not receiving the shipping notification for something I received last night, I have decided to try disabling Postfix’s HELO validations on my server. This will likely lead to far more spam being delivered, but it should eliminate odd rejections from non-compliant servers.
I had smtpd_helo_restrictions = reject_invalid_hostname, reject_non_fqdn_hostname set, which can be referenced here. The problem was some sites wouldn’t send a proper HELO, leading to mail not being delivered as it should have been. Maybe it’d be best to have a SA rule which marks down improper HELOs instead of simply blocking them.
If spam levels get too high again, maybe I’ll go back to the old restrictions. They generally work fine.
You’d be surprised at who in corporate email america aren’t sending out proper HELO’s. Dealing with that right now with a client.
My biggest problem previously was that Outlook Express doesn’t. Legit users with OE who use me as their first hop were sending HELOs which were equal to the machine name, without anything else. There doesn’t seem to be a way to change it either.
I had these folks either switch to Thunderbird or just use webmail.