Plesk 12.5 Email Server listed in CBL -- Shared Hosting Question

[G J Piper]

I have Plesk 12.5.30 running CentOS6.7 with Dovecot and Postfix as the mail server, and it is only one month old. I found my IP was just listed today in the http://www.abuseat.org CBL. I "delisted" it for now, but I fear it getting listed again. I got this message, and am wondering what server setting I should use to remedy this:

From the CBL:
"If this is a shared hosting IP address, make sure that your mail server software is set up to identify _itself_ in its mail connections, not each of your customers."

Does it have something to do with this setting:



How can I see if my server is identifying itself correctly? I don't see much SMTP traffic. There is only one IP address for this server. (76.12.176.253)

 

[Alex@Plesk]

Hello, all required Postfix configuration is performed by Plesk. This is a quote from article http://www.binarytides.com/install-postfix-dovecot-debian/ about Postfix identifying:

The following parameters are the 3 super confusing parameters that you need to understand and configure properly to avoid unexpected problems.

myhostname
mydomain
myorigin

You could be hosting multiple domains on your server, say abc.com + efg.com + xyz.com. You have to use one of them as a primary domain and use it for "myorigin". The myorigin field is the one that is configured automatically while postfix installs and asks you for the domain of the server.

By default myorigin is configured to point to /etc/mailname so you can either fill in your default domain in /etc/mailname or specify in the configuration file directly.

The domain specified with myorigin is used for mails generated by Postfix. For example when it fails to deliver a mail, it would reply with a from address of "Mail Delivery System<MAILER-DAEMON@myorigin>".

The myhostname parameter is supposed to contain the your "mail server name" as indicated by your mx record. This is the name that Postfix uses in smtp communication to identify itself. For example "HELO myhostname".

If you set myhostname to a certain domain, then you should be able to setup the SPF records for that domain later. This is dictated by the SPF specifications.

You might as well leave myhostname to just "localhost" and things would still work just fine. However in that case your server would use a message like "HELO localhost" when connecting to other mail servers like gmail, and gmail would angrily reject the mail calling it unsolicited.

Therefore it is recommended to configure myhostname to a proper domain name with valid A and TXT (SPF) records. Also make sure to set myorigin.

Example configuration -

myhostname = mail.yoursite.com
myorigin = yoursite.com

Technically, on a single a server, you can use the same value of myorigin for myhostname. However in diverse setups involving multiple separate servers, the values of these fields need to setup more carefully.

To learn more read the Postfix basic configuration guide.

So in other words, in your case, you can choose the option 'Send from the specified IP address' and choose your IP. Make sure that your hostname is correct. Also, make sure that your server is not the source of spam setting Outgoing Mail Control.(Tools & Settings > Mail Server Settings)

 

[G J Piper]

Hello, all required Postfix configuration is performed by Plesk. This is a quote from article http://www.binarytides.com/install-postfix-dovecot-debian/ about Postfix identifying:

So in other words, in your case, you can choose the option 'Send from the specified IP address' and choose your IP. Make sure that your hostname is correct. Also, make sure that your server is not the source of spam setting Outgoing Mail Control.(Tools & Settings > Mail Server Settings)

Thank you. I have changed my setting from "Send from domain IP addresses and use domain names in SMTP greeting" to "Send from domain IP addresses". There is only one IP address for the server. The hostname is correct, and I've done HELO and email tests to verify. After 3 consecutive days of getting listed in the CBL, I'm hoping this cures my server. I've already Turned on the Outgoing Mail Control and see nothing sending many emails out per hour. There are (and presumably have been) only about 20 emails going out for the entire server per hour -- and that includes about 25 domains.

 

[G J Piper]

I'm just leaving this message as a follow-up. I've been in contact with the people from the CBL (www.abuseat.org) and through testing with my server they have confirmed that the proper setting to NOT get listed on the CBL Block List is to have the "Outgoing Mail Mode" set to "Send from domain IP addresses."

Using the setting of "Send from domain IP addresses and use domain names in SMTP greeting" will almost certainly get you on the CBL Blacklist every day it is turned on. Beware.

Even Plesk's own version 12.5 online manual says complete misinformation in regard to these mail settings. Spamhaus and the CBL people are aware of this and say they will be in contact with them to get Plesk's instructions ammended or corrected to reflect reality.