Reverse dns does not match smtp banner как исправить

Why SMTP Reverse DNS Mismatch Reverse DNS does not match SMTP Banner?

But as far as I can see my rDNS for the IP address are both the same: mail.simplyislam.biz I am at a loss as to how to fix the issue please ?

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asked May 14, 2015 at 19:53
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Your server is closing the connection right after the client sends the helo and never sends the helo itself. This is a misconfiguration of your mail server, not in DNS.

May 14, 2015 at 20:20
@sebix his DNS configuration is funny anyway 😉 Check my answer.
May 14, 2015 at 20:23

2 Answers 2

Reverse DNS does not match SMTP Banner

The SMTP Banner is the response of your mail server for the ehlo query. Currently your mail server is closing the connection. That is the reason for the mismatch between rDNS and SMTP banner. Reverse DNS itself is set up correctly, though.

# telnet mail.simplyislam.biz 25 Trying 178.32.48.104. Connected to mail.simplyislam.biz. Escape character is '^]'. ehlo example.com Connection closed by foreign host.

Having looked a little deeper, your DNS and mail server configuration seems a little messy:

> set type=mx > simplyislam.biz … simplyislam.biz MX preference = 0, mail exchanger = mail.simplyislam.com simplyislam.biz MX preference = 90, mail exchanger = mail.simplyislam.biz > mail.simplyislam.biz … simplyislam.biz MX preference = 0, mail exchanger = mail.simplyislam.com simplyislam.biz MX preference = 90, mail exchanger = mail.simplyislam.biz > simplyislam.com … simplyislam.com MX preference = 5, mail exchanger = simplyislam.biz simplyislam.com MX preference = 30, mail exchanger = mail.simplyislam.com

Your domain (the part behind the «@» in an email address) needs a MX record pointing to your mail server:
simplyislam.biz. 3600 IN MX 10 mail.simplyislam.biz.

Then you need an PTR record pointing your IP address to your mail server, but that does already exist:
104.48.32.178.in-addr.arpa. 3600 IN PTR mail.simplyislam.biz.

Your mail server address does not need an MX record, unless you are expecting emails sent to «@mail.simplyislam.biz».

Of course you need to do the same things for your primary mail server «mail.simplyislam.com».

SMTP Reverse DNS Mismatch Postfix

Доменные имена у хостера были недоступны в теч. дня. Потом их подняли и на сервер стал приходить спам в немыслимом кол-ве.

При выполнении smtp-диагности выдает следующее:

SMTP Reverse DNS Mismatch Warning - Reverse DNS does not match SMTP Banner

Провайдер говорит, что с PTR на их DNS-х все в порядке. И сама почта работает. Просто приходит спам.

Вопрос — в чем может быть причина такой ошибки и как ее исправить? Подозреваю, что это как-то связано с тем, как сервер представляется в EHLO и оно не соответствует PTR-ке у провадера.

Resolved Reverse DNS does not match SMTP Banner

It would appear that I have this problem on my Plesk server, and I can’t figure out what’s causing it.
I recently tried replying to an email and got a message saying my email was rejected — I assume this is the cause

With that said, could someone help me troubleshoot and fix this?

Martin Dias

QA Engineer

Staff member

SMTP Banner is normally the hostname, and it should be a FQDN in an best case scenario.
Reverse DNS needs to be set normally over the Server Providers Panel or Support

You can check the SMTP Banner with:

# telnet localhost 25

Here as an example:

root@mail ~ # telnet localhost 25 Trying 127.0.0.1. Connected to localhost.localdomain. Escape character is '^]'. 220 mail.example.com ESMTP Postfix quit 221 2.0.0 Bye Connection closed by foreign host.

Here the Banner is mail.example.com

The hostname can be changed over Tools & Settings > Server Settings and over CLI

# hosnamectl set-hostname mail.example.com

the PTR/Reverse DNS can be checked with:

# host

Here as an example:

root@mail ~ # host 203.0.113.2 2.113.0.203.in-addr.arpa domain name pointer mail.example.com.

JohnBee

Basic Pleskian

Hi and thanks so much for helping out with this.
I ran the tests and found the following;

# telnet localhost 25

Connected to localhost.localdomain.
Escape character is ‘^]’.
220 webshot-5eb7aafc891d2.local ESMTP Postfix

I then looked in Tools & Settings, and found that hostname was indeed properly set with my.hostname.net
I then ran the following command:

# hosnamectl set-hostname my.hostname.net

Then verified with the following:
# host

And receive the following response
157.136.141.99.in-addr.arpa domain name pointer my.hostname.net.

With that said, it would appear that my Postfix banner is reporting the webhost hostname rather than the set hostname
Any idea what could cause this, or how I might fix it?

What does the Warning – Reverse DNS does not match SMTP Banner mean? – SMTP Diagnostic Tool

The short answer is that the reverse IP address name is not contained in the server HELO or EHLO banner. In the example below, the string “someotherdomain.com” is not found anywhere in the server banner, which is reporting “example.com“. This is only a warning, and in some cases you may have no control over this. However, if you have the ability to make these match, you should. Some mail servers look for this and use it to mark messages you send as questionable. Most mail systems will not reject your messages outright, but this may effect your spam score increasing the likelihood your messages will be marked as spam.

In other words, it is a best-practice you should endeavor to follow. It doesn’t mean you are a bad person or won’t be able to send email.

220 mx.example.com StrongMail SMTP Service at Wed, 09 Sep 2009 17:00:01 -0700

Not an open relay.
0 seconds – Good on Connection time
0.156 seconds – Good on Transaction time
OK – 1.2.3.4 resolves to mail.someotherdomain.com

If you are not sure where to access your SMTP banner in your mail server, read below for some helpful hints. We do not advise making ANY changes to your mail server if you are not the system administrator or confident in making these changes.

Configure SMTP banner Exchange 2003

Open Exchange system manager.
Expand your administrative group (”First administrative group” by default).
Expand Servers.
Expand “YourServersName”.
Expand Protocals container.
Select SMTP container.
On the right window, right click the Default SMTP virtual Server (Or the name you set your SMTP Server) and select Properties.
Select the Delivery Tab.
Click the Advanced button.
Under the Fully Qualified Domain Name (FQDN) type mail.yourdomain.com (The A/Host record you created in DNS for your mail server)
Click Apply and OK again to accept the changes

Configure SMTP banner Exchange 2007/2010

Open the Exchange management console.
Select the Organisation Configuration container.
Select Hub Transport container.
On the right select the Send Connectors tab.
Right click your send connector and select properties.
On the General tab under the Set the Fully Qualified Domain Name (FQDN) this connector will… type the A record domain name you created. Which in our case is mail.yourdomain.com. Click OK.
Under the Server Configuration container click the Hub Transport container.
In the Right window Select the properties of the Receive Connector under Receive Connectors tab.
On the General tab under the Set the Fully Qualified Domain Name (FQDN) this connector will… type the A record domain name you created. Which in our case is mail.yourdomain.com. Click OK.

To verify these changes we would recommend using our SMTP Diagnostic Tool again.