I got the 521 5.5.1 Protocol error right after I type E for EHLO.
It's working locally.
Nothing too special other than the fact that postscreen is handeling the mail and not postfix/smtp
It's looking very good on your side.
This is exactly the behavior I'm expecting.
Thank you for your detailed example!
To be honest - I tried way too many configuration changes, and I reverted them - but in vain.
I just installed it (iRedMail 0.9.8) from scratch with the following configuration:
SELINUX and firewalld disabled
All of the packages are updated (yum update -y)
default mail storage path
Nginx web server
Optional componenets: Roundcubemail and iRedAdmin (without netdata and Fail2ban)
This always fails - I can't connect to the server via SMTP or web, so I installed with all of the default optional components (also netdata and Fail2ban) - and it always works - I can connect to it via SMTP and web. (I'll open another post for them so they'll know about it)
And now I'm back to where I started - it's working locally, but when trying remotely I'm getting:
451 4.7.1 <firstname.lastname@example.org>: Recipient address rejected: Intentional policy rejection, please try again later
or if you prefer, from /var/log/maillog:
May 16 19:45:19 il-lab-mail postfix/smtpd: NOQUEUE: reject: RCPT from unknown[10.40.0.109]: 451 4.7.1 <email@example.com>: Recipient address rejected: Intentional policy rejection, please try again later; from=<firstname.lastname@example.org> to=<email@example.com> proto=ESMTP helo=<mail.englab.forescout.com>
According to their Errors you may see while maintaining iRedMail server page I just should retry - but it won't work.
According to their answer in this forum (link) it's greylisting, and it can be disabled.
So I did it in combination with other suggested methods they suggested in their documentation - and this is how I got the 521 5.5.1 Protocol error...
Anyway, I'm going way to off topic now.
I'll try with the new setup and with minor configuration changes while I backup and revert if needed.
Thank you for your assistance.