Is it safe (or mostly safe) to simply block attempts to deliver mail with a helo that is only an IP address? (I am talking about only on postfix/stmpd and obviously not on postfix/submit or related).
On 18.11.19 13:22, Gregory Heytings wrote:
No it is not, it's a RFC violation. The string that follows HELO/EHLO is purely informational, it should not be used for any filtering purpose.
can you provide RFC and section? AFAIK the only violation is if you reject based on HELO string not equivalent to reverse resolution of connecting client and other helo string rejections are fine from RFC point of view.
If you use it for this, you'll end up rejecting legitimate emails.
this can happen anytime anyone rejects any e-mail. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. Chernobyl was an Windows 95 beta test site.
