Your reverse DNS does not match with your sending domain, rDNS already setup correctly

[anthonyinit2012]

SYSTEM INFORMATION
OS type and version	Ubuntu Linux 22.04.5
Webmin version	2.303
Virtualmin version	7.30.8
Webserver version	Apache
Related packages	???

Hi all,
I know this has been discussed before but my issue is slightly different.

Mail tester showing warning, “Your reverse DNS does not match with your sending domain”

My rDNS already setup correctly and i have the option to change it from my ISP. it has been done month ago.

However mailtester showing warning.

My rDNS name is server.mydomain.com but the mail sent from mail.mydomain.com

I don’t want to change my rDNS to mail.mydomain.com since this is not only a mail server this has my main official domain.

can someone help me figure out what’s going on from my vistualmin and mail setup? maybe i can change HELLO: mail.mydomain.com to HELLO: server.mydomain.com

I have another server with the same setup and that has no issue with mailtester. no warning.

Thank you

[stefan1959]

Is the hostname on the server mail.mydomain.com, you could rename the hostname to match the reverse or visa versa.

My score is 10/10 but I get your warning. I might try change my reverse name and see what happens.

My systems nerver had any issue getting mail sent, if gmail except your email the 99.9% of other systems will except.

P.S. I changed the reverse name to match the hostname and that warning went away.

[verne]

is this a cosmetic non-issue? that is, do you know if any vendor is refusing to accept your mail?

having just said that, I do recall we had one recipient like 10 years ago our clients tried to send mail to that did require the rDNS record to match exactly

[ID10T]

[Joe]

Your tester is probably wrong. The language it uses to describe what’s going on is ambiguous, and your anonymization makes it so I can’t glean it from the actual values they’re showing, either, so I can’t be sure about what it’s suggesting is wrong.

But, I can tell you that no major mail server (and no sanely managed small one) will block email based on the PTR not matching the from: field in email. That would be insane and would block 90% of email. It’s literally stupid to claim this matters (and that’s what it seems like it’s saying).

If it means your HELO/EHLO hostname doesn’t match the PTR, that’s also not a big deal and won’t cause email to be blocked. But, some people do like to have it match for the sake of tidiness. This just means you set your PTR to match your system hostname.

You don’t have the option of having it be all your domains. It has to be some single name (PTR can only ever be one name, more violates spec and expectations, and there’s only one system hostname and you shouldn’t try to override it for HELO/EHLO in the general case). So, if you want it to look “nice”, set your system hostname and the PTR to the same thing (but not anything you are virtually hosting in Virtualmin).

[Joe]

Don’t override hostname things in the Postfix configuration. Set your actual system hostname and PTR to the thing you want.

Changing any of myhostname, mydomain, mydestination, etc. is very likely to break delivery of virtual mail, because it trickles through various other options (they become variables, $myhostname, that affect other options). There’s no good reason to do it when you can just choose to use the hostname you want to use.

[ID10T]

@Joe

Set your actual system hostname and PTR to the thing you want.

Isn’t that what the first option pictured is for? In my case /etc/mailname shows my server/host name already.

@anthonyinit2012

My rDNS name is server.mydomain.com but the mail sent from mail.mydomain.com

I don’t want to change my rDNS to mail.mydomain.com since this is not only a mail server this has my main official domain.

[Joe]

Nothing in the Postfix module can ever set the system hostname. It changes Postfix options. /etc/mailname is not setting the system hostname, but it should generally match the system hostname.

[stefan1959]

I’ve always changed Hostname here, I never touch postfix.

[anthonyinit2012]

I think i found the issue. /etc/postfix/master.cf

submission      inet    n       -       y       -       -       smtpd -o smtpd_sasl_auth_enable=yes -o smtpd_tls_security_level=may
smtps   inet    n       -       y       -       -       smtpd -o smtpd_sasl_auth_enable=yes -o smtpd_tls_security_level=may -o smtpd_tls_wrappermode=yes
smtp-17348532403142	unix	-	-	y	-	-	smtp -o smtp_bind_address=9x.xxx.xx0.xxx -o smtp_bind_address6=2xxx:xxxx:2xxxx:1xxx::1 -o smtp_helo_name=mail.mydomain.net

after changing the last line mail.mydomain.net my issue with mailtester is gone. i don’t see anymore warning. PASS 10/10

Thanks

[ID10T]

@stefan1959

I’ve always changed Hostname here, I never touch postfix.

It wasn’t about changing the host name. It was about changing the Postfix ‘from’ name. I thought what I pointed to would do that via the interface.
“What doman to use in the outbound mail”.

[Joe]

Everything works if you let it.

[Joe]

@ID10T

It was about changing the Postfix ‘from’ name.

It’s about HELO/EHLO name. Not “from”, which comes from a header in the email (literally, the email client sets it).

@ID10T

I thought what I pointed to would do that via the interface.

It would (change HELO/EHLO), but you generally shouldn’t do that. You should change the system hostname to be what you want HELO/EHLO to be. Messing with myhostname, mydomain, mydestination, myorigin is likely to cause confusion and delivery problems with virtual mail.