I have some problems sending emails from my server: I've been banned/suspended for abuse (IP blocked) by the SMTP server. This happens only on my new virtual server.
Right to the question: is my new server misconfigured? How can I fix it, hoping that this would fix the suspension problem as well?
The story:
New server Received header
This is part of the headers of a message sent from a PHP script running on my private virtual server:
Received: from apogeo.hpsart.it (31-193-130-251.static.as29550.net
[31.193.130.251])
The weird part is the 31-193-130-251.static.as29550.net instead of the hostname. SMTP server/client interaction:
SERVER -> CLIENT: 220 smtps.pec.aruba.it ESMTP Postfix
CLIENT -> SERVER: EHLO apogeo.hpsart.it
[...]
SMTP ERROR: RCPT TO command failed: 554 5.7.1 <31-193-130-251.static.as29550.net
[31.193.130.251]>: Client host rejected: IP address banned for abuse. Please
contact the support or use the Webmail
/etc/hosts is correctly configured (I guess). I think it could the reason of the suspension I'm not an expert but:
127.0.0.1 plutone plutone.iosystems.it localhost localhost.localdomain
::1 plutone plutone.iosystems.it localhost localhost.localdomain
Old server Received header
Old server works fine and never got suspended/banned. Headers show the correct hostname:
Received: from apogeo.hpsart.it (guest2.iosystems.it
[81.31.150.182])
File /etc/hosts is nearly identical.
Update 1: as suggested by @Tero Kilkanen I've changed the Reverse DNS (it was blank) from 31.193.130.251 to plutone.iosystems.it. It doesn't work: Recevied always shows 31-193-130-251.static.as29550.net instead of the hostname.
The problem is that your forward and reverse DNS entries are not the same. It is essential to have have the IP to DNS and DNS to IP mappings the same with E-Mail.
You should ask your hosting provider to set up the proper reverse DNS (sub.domain.com) for your server IP address.