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I have a VPS running CentOS. This server has a hostname of server.domain.com and an IP of 1.1.1.1.

I have a dedicated IP address on the server of 2.2.2.2 which runs a domain second.com. Second.com, is my main domain. I use this domain to send mail. I am trying to configure this as my main mail domain but I cannot get my SMTP reverse banner to work- it keeps showing server.domin.com

Is it ok to have my server hostname for my reverse smtp banner? On windows, this is something I do not do- I set everything to line up to one A record mail.domain.com.

Does anyone know how to configure Exim to do what I am asking? I of course read http://docs.cpanel.net/twiki/bin/view/AllDocumentation/WHMDocs/EximDifferentIps which did nothing.

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It is find to have your server hostname for the SMTP banner. You should verify that the PTR record for the IP returns the server host name. Configure the MX record for your domain to return the server hostname.

If you have configured SPF, which you should, allow your MX to send email for the domain.

Normally, you want the fully qualified domain name of the mail server to be a subdomain (host.example.com, rather than example.com). Otherwise, your server will look spammish. It is common for the MX for a domain to belong to another domain.

If you do want to use the domain interface, your can configure the interface variable to your domain's IP address. Verify the PTR record, points to a name which resolves back to the address. Typically, this would be in the form mail.example.com or smtp.example.com, but it could be any name you choose. Try not to your web server names. There is nothihg wrong with having multiple names returning the same IP address.

You can override the banner message by setting the smtp_banner variable. This option will change the name based on the address it is listening on:

smtp_banner = ${smtp_active_hostname} ESMTP Server Ready ${tod_full}

You can find additional information in the Exim documentation.

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Thanks! I think I got it now- my domain is virginiaseo.org and my MX is pointing to mail.virginiaseo.org which I have mapped to my MAIN SERVER IP, not the dedicated IP I run my site on. I then have a reverse DNS record mapping that IP to my server hostname. So as of right now, all my check marks are green in MxToolbox, reverse SMTP and DNS match. So the solution was to set the actual server hostname as the reverse SMTP instead of trying to juke it to be the dedicated IP address as reverse SMTP.

What I was trying to do was to map my mail server to my DEDICATED IP, and use a reverse DNS and SMTP banner of mail.virginiaseo.org. This did not work at all, so I gave up. Coming from Windows Admin of Exchange, I typically map a MX to mail.domain.com, then point an A record at my server IP. Then for my SMTP HELO response, I use mail.domain.com and when I look at a mail header I see my HELO/EHLO as mail.domain.com. Now further down in the header I of course see the sending server hostname which is like exchange.dom.local but that is besides the point.

So in reality I was trying to apply Windows concepts to Linux. This all stems from my server being compromised and sending spam- as long as things are matching up so I am not flagged as spam I am good to go! Thank again!

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  • Thanks for sharing your final solution, although 1) it's a little unclear what you did and 2) most of the background info should probably move to comments. Jul 16, 2014 at 18:30

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