When i send massage in my work mail to gmail.com domian, my massage is back and in it the following. I have no idea what to do with it, I thought the problem was in the mailcow version, but when I updated the problem remained. This is the mail system at host mail.chnpu.edu.ua. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system : host gmail-smtp-in.l.google.com[64.233.164.27] said: 550-5.7.25 [91.192.47.142] The IP address sending this message does not have a 550-5.7.25 PTR record setup, or the corresponding forward DNS entry does not 550-5.7.25 match the sending IP. As a policy, Gmail does not accept messages 550-5.7.25 from IPs with missing PTR records. For more information, go to 550-5.7.25 https://support.google.com/a?p=sender-guidelines-ip 550-5.7.25 To learn more about Gmail requirements for bulk senders, visit 550 5.7.25 https://support.google.com/a?p=sender-guidelines. 38308e7fff4ca-2f3e2fdae4asi13409461fa.203 - gsmtp (in reply to end of DATA command)

``` Gmail does not accept messages 550-5.7.25 from IPs with missing PTR records ``` You have to set a PTR entry for your mailcow

@"DocFraggle"#p17889 as far as I understand it is established[upl-image-preview url=https://community.mailcow.email/assets/files/2024-08-21/1724230604-107839-image.png]

@"DocFraggle"#p17896 the server is at work

problem with send massage to gmail.com domian

konsist

DocFraggle as far as I understand it is established

DocFraggle

Whenever you set this up, it doesn’t work

https://mxtoolbox.com/supertool3?abt_id=AB-631B&abt_var=Variation&run=toolpage&action=smtp%3A91.192.47.142

konsist

DocFraggle and how should I solve this problem, I understand that I need to change the PTR record, but how to do it and where?

DocFraggle

It depends on where your mailcow is hosted. If you use a VPS/VM/Server you normally set the reverse entry at your hosting provider

konsist

DocFraggle I use the server, I called my Internet provider and the support service said that there are no blocks from their side

esackbauer

konsist I use the server, I called my Internet provider and the support service said that there are no blocks from their side

Your mail server IP address belongs to Neocom:
https://apps.db.ripe.net/db-web-ui/query?from=www&searchtext=91.192.47.142

Have you been in touch with them? They should be able to set up a reverse DNS entry for you.

DocFraggle

So your server is running at your place then? Or did you rent the server somewhere?

konsist

DocFraggle the server is at work

DocFraggle

And who is responsible for your DNS at your work? Maybe ask them

konsist

DocFraggle according to the idea, I answer, I came to replace the system administrator, and he left me nothing but passwords

DocFraggle

I’m very sorry, but we can’t help you figure out the DNS concept used by your company… maybe ask your ex-employee?

konsist

esackbauer so I contacted them, talked to them about the PTR recording, to which they said that there are no blocks from their side

DocFraggle

konsist no blocks from their side

What do you mean by blocks? If you are referring to a firewall block or something like this, this has nothing to do with it!
If you got your server from Neocom they are responsible for the network block which @esackbauer mentioned, and can set a PTR record for your IP in their DNS server

DocFraggle

konsist FYI, this is a way to check which DNS server is responsible for a network:

dig -x 91.192.47

; <<>> DiG 9.18.28-1~deb12u2-Debian <<>> -x 91.192.47
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 51200
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;47.192.91.in-addr.arpa.                IN      PTR

;; AUTHORITY SECTION:
47.192.91.in-addr.arpa. 3600    IN      SOA     ns.neocom.net.ua. hostmaster.neocom.net.ua. 2023120401 7200 3600 1209600 86400

In your case it’s

ns.neocom.net.ua

So their tech support should be able to help you

esackbauer

That is crazy, because my RIPE Link does show that your mail server IP is in their IP block.

konsist

esackbauer where did you see that the ip is blocked?

esackbauer

I don’t mean it is blocked, I mean it is a block of IP addresses.
https://larus.net/blog/what-is-ipv4-block

konsist

esackbauer do you mean a group of ip addresses?

esackbauer

Yes… Did you actually read my last link?