While I agree with most of what scasey says, I don't agree with his view on the PTR. The PTR should reflect your domain. Of course that e-mails could get through nonetheless, because usually e-mail servers do not make decisions based only on one criterion, usually they work with weights and after a certain point they consider an e-mail suspicious and it gets greylisted or rejected. You can get e-mails through also if you don't have an SPF record, but that doesn't mean you shouldn't.

Check this out:
http://social.dnsmadeeasy.com/blog/d...ail-marketing/
Or even better, mxtoolbox, probably the best known site where you can check if your e-mail server settings are valid:
https://mxtoolbox.com/problem/smtp/s...dns-resolution

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vincix,
Your analysis is correct, if a mail server checks rDNS, it compares the IP address of the connecting server to the IP address returned by the rDNS check. It does not care, however, what the domain name on the PTR record is and doesn't check that at all.

As the OPs IP has an rDNS, there is no problem for them to solve, and no need to ask their ISP to change the domain on the PTR record, as stated.

Putting their domain into the mxtoolbox site will show that all is well, I expect. That's a good tool to share.

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After installing everything I usually have the following data from mxtoolbox, mecsa and mail-tester on rDNS.

Although it looks good overall, rDNS shows up as a problem.

I did tests sending mail to friends, they reach the spam folder and some do not receive them.

I suppose I will ask the IP provider for a solution, but before doing this I don't know if there is another option?

Thanks for the help

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Interesting.
I have one rDNS referencing one domain. All mail to any domains I host hit that domain's mail server. In my case the SMTP banner does match the rDNS (both say mail.mydomain.com), so I get a green check mark and a warning that the banner/rDNS is different from the domain in the MX record.

Since you have a static IP, you should probably request that the rDNS reflect the same domain as your mail server.
(and perhaps I should update the MX records to reflect the actual domain name the server is using)

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It is true that one of the main requirements for a mail server is the correct configuration of the rDNS to prevent our mail from reaching SPAM.

The truth is that I am not worried that it will reach SPAM because the people who receive it know that I am going to send it, but I am concerned that the mail will not arrive.

I've been trying to understand how DANE and DNSSEC work for several days, maybe it works to improve the delivery of emails

So you mean to reflect, let's say, mailrelay.domain.com, instead of domain.com, right?

I think I missed this again.

mydomain.com: Domain name, not the server subdomain
mail.mydomain.com: Mail server subdomain name (hostname -f)
ht.northwestel.net: Internet provider name, the same one that gives me the static public IP.

At the server level will I have to add ht.northwestel.net somewhere?

Or should I play MX Records by adding ht.northwestel.net.?

Or is it better to talk to the provider to make changes to mail.mydomain.com?


Cheers

A good premise (at least this worked for me when I eventually wanted to understand the difference) is to realise that the e-mail server's domain name can be anything. It doesn't have to be mail.mydomain.com, it can be whateveryouwant.anotherdomain.com. As long as it is allowed (through SPF, DKIM, DMARC whatever + the right rDNS) to send e-mail, that's fine.


This ht.northwestel.net you don't need to use anywhere.
If you want to change your rDNS you need to talk to your provider anyway. I don't understand exactly what you mean by "play". In any case, I still think that the standard way of doing this is to talk to your provider and ask them to change your rDNS to mail.mydomain.com, so that the ip of your e-mail server is resolved to "mail.mydomain.com".

If they refuse (I'm not sure if they are in any way bound by this), then I suppose you could change your smtp banner to that of the name given by your ISP. (I guess this is what you were referring to in the first question?) A compromise which kind of sucks, to my mind, but it would work, as far as I can tell

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I did the test with smtp_banner:

nano /etc/postfix/main.cf

smtpd_banner = $ d200-100-40-30.yt.northwestel.net ESMTP $ mail_name (Raspbian)

And now they greet each other well, the error shown in mxtoolbox is no longer there.
In mail-tester it stays the same with the rDNS error.

I don't know how this change could affect the rest, but I'll be aware.


Greetings and thanks