Full Disclosure: Setup of email servers is something fairly new to me, so go easy on me :)
Recently users reported that they were not receiving emails from my site. The site runs a vbulletin forum so the emails are things like subscription notifications etc.
After doing a little digging I have found two issues, that I am not certain how to fix:
Issue #1 According to this:
https://mxtoolbox.com/SuperTool.aspx?action=smtp%3a77.68.13.98&run=toolpage#
The SMTP banner check fails as "Reverse DNS does not match SMTP Banner". As I understand it some mail server will rDNS check the sender and reject if there is not match. However, I have no idea how to resolve this.
Issue #2 Checking /var/log/maillog I am seeing quite a few entries that a similar to this:
Sep 3 03:39:00 mail postfix/smtp[48940]: 53D9554E2C: host mx.mnd.ukmail.iss.as9143.net[212.54.58.11] refused to talk to me: 550 mx6.mnd.ukmail.iss.as9143.net mx6.mnd.ukmail.iss.as9143.net logid=SMTPRC 550 MXIN102 Your IP 77.68.13.98 is in RBL. Please see https://www.spamhaus.org/query/ip/77.68.13.98 ;id=wfhofcY9kJpgl;sid=wfhofcY9kJpgl;mta=mx6.mnd;d=20180903;t=053912[CET];ipsrc=77.68.13.98;
From this it seems that the server IP has been blacklisted, following the spamhaus link in the maillog entry led me to:
https://www.abuseat.org/lookup.cgi?ip=77.68.13.98
This gave me the option to remove the listing
So, my somewhat vague and inexperienced question is what do I need to do to fix this?