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I have a self hosted mail server on a VPS. When sending mail through an application, most of my mail is getting rejected by google. Google is giving following message about the mail.

Reporting-MTA: dns; mail.myclearmargin.com
X-Postcow-Queue-ID: BAC4E881209
X-Postcow-Sender: rfc822; no-reply@myclearmargin.com
Arrival-Date: Mon,  8 Aug 2022 00:03:09 -0700 (PDT)

Final-Recipient: rfc822; alauddin088@gmail.com
Original-Recipient: rfc822;alauddin088@gmail.com
Action: failed
Status: 5.7.25
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.25 [2a02:c206:2061:6136::1] The IP address
    sending this message does not 550-5.7.25 have a PTR record setup, or the
    corresponding forward DNS entry does 550-5.7.25 not point to the sending
    IP. As a policy, Gmail does not accept 550-5.7.25 messages from IPs with
    missing PTR records. Please visit 550-5.7.25
    https://support.google.com/mail/answer/81126#ip-practices for more 550
    5.7.25 information. z4-20020a05640240c400b0043d9832325fsi6139125edb.541 -
    gsmtp

But both of my forward DNS and reverse DNS looks okay.

host mail.myclearmargin.com
mail.myclearmargin.com has address 194.163.151.74

host 194.163.151.74                                   
74.151.163.194.in-addr.arpa domain name pointer mail.myclearmargin.com.

Can anyone help me out what could be the problem?

Note: When using this command host mail.myclearmargin.com, after sometimes it also returning connection timed out; no servers could be reached

1
  • More knowledgable people seem to have given answers; However, I do believe you don't have a PTR record properly configured. Given the details you provided, I cannot do a reverse lookup for that IP. Not worth an answer, but PTR, SPF, DKIM and DMARC help guarantee delivery. There are tools that can help diagnose issues, like mail-tester.com and others. (I have no affiliation with mail-tester.com).
    – GCon
    Aug 10 at 16:11

1 Answer 1

11

As you can see from Google’s diagnostic, you are using IPv6 to send the mail.

Using dig +short mail.myclearmargin.com. aaaa to look for your AAAA records, I’m not getting any addresses. This might well be the problem.

Set up the necessary AAAA record (IP address 2a02:c206:2061:6136::1) or configure your MTA to use IPv4 only.

Also: your SPF record, too, only allows IPv4 senders:

$ spftrace myclearmargin.com 2a02:c206:2061:6136::1
myclearmargin.com
│   "v=spf1 ip4:194.163.151.74 -all"
├── ip4:194.163.151.74 not-match
└── all match result=fail
fail
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  • Can you give me some link/article/tutorial how to setup those! I don't have much knowledge on server related issues. Only following tutorials to develop something. Aug 9 at 16:05
  • 7
    I think you will easily find answers online by searching for ‘set up AAAA records for domain’ and ‘ip6 mechanism in SPF record’ or similar phrases. Be aware that running a mail server should not be done lightly, you must have solid admin skills to do so.
    – glts
    Aug 9 at 16:14
  • It's always DNS.
    – Sagar
    Aug 10 at 1:50
  • 1
    @Sagar No it is not DNS here. It is policy from remote mailer to require both backward and forward proper resolution, which does happen to be using the DNS, but the policy certainly does not come out of the DNS as a protocol, just its use. Aug 10 at 17:07
  • @Sagar that's just a meme with little real-world relevance
    – user253751
    Aug 10 at 17:40

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