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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?

MrEyes
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1 Answers1

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Blocklist Lookup Results

77.68.13.98 is not listed in the SBL
77.68.13.98 is not listed in the PBL
77.68.13.98 is not listed in the XBL

Based on the current results your issue #2 is already solved. Good. Sometimes it's not that easy as many RBLs are fully automated i.e. only removing an entry if no active SPAM seen on specific interval. Some use very long intervals and it's up to the receiver which listings they use; how aggressive they want to be.

The issue #1 SMTP banner mismatch has two approaches:

  1. Fix the reverse DNS PTR record to match the SMTP banner. Your ISP needs to support custom reverse records. You must ask them to do it for you.

  2. Fix the SMTP banner to match the current PTR record. Easy to do, no other disadvantages than the less cool Received: header that no-one who would care reads anyway.

Both of the above requires a matching A record.

Esa Jokinen
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