Has main.cf been changed in recent releases (ISPCOnfig 3.1.5/3.1.6)? I have started seeing some valid emails being rejected with 'Helo command rejected: Host not found'. I can solve the problem by removing the reject_unknown_helo_hostname restriction from main.cf. I understand the reasons for having this restriction but there are still plenty of mail servers that are poorly configured such that this restriction causes problems. So has ISPConfig made a conscious decision to add this restriction? Thanks, Cliff
This has been changed some time ago to improve spam filtering, must be several versions before 3.1.5 if I remember correctly. And yes, this change is intended as it stops a lot of SPAM. Senders that do not have their servers configured correctly are probably not able to reach most other mail servers anyway and they will fix it quite soon when they get their mail back as undeliverable. But if you want to allow sending to your server from systems with unknown helo addresses, then you can alter that in the main.cf file you might want to copy an adjusted <osname>_postfix.conf.masterfile from install/tpl/ in the ispconfig tar.gz file to /usr/local/ispconfig/server/conf-custom/install/ to ensure that your changes don't get reset on ISPConfig updates.
OK, thanks Till. Unfortunately one of the culprits is HSBC bank and I don't think they'll take much notice of me telling them to fix their mail config! But you never know
