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  1. #1
    Join Date
    Jan 2008
    Posts
    42

    * Server's hostname/nameservers affect mail deliverability?

    Hey guys... our company is ordering a new dedicated server and we are a little unsure what we should choose as far as the full hostname and nameservers of this one server.

    This server will have a couple different websites on it, but really, there is only one BIG website on it... let's call it abcd.com.

    While most would pick a hostname of host.abcd.com for instance, if at all possible, we would like the domain name part of the hostname to be something different than abcd.com. We own a domain name that doesn't point to anything yet (unuseddomain.com) and we were wondering if we could use that domain in our hostname.. host.unuseddomain.com.

    And instead of using abcd.com as the domain name for our own nameservers (ie. ns1.abcd.com, ns2.abcd.com), we would like to again, use the unused domain name we own (unuseddomain.com) for the nameservers domain name: ns1.unuseddomain.com, ns2.unuseddomain.com.

    So...

    Will this work? Is this perfectly acceptable?

    And lastly...

    Since the one website we really care about on this server (the one we got the server for in the first place) is abcd.com, is using the unuseddomain.com for the hostname and nameservers (as above) a bad choice in anyway regarding email deliverability? I understand that mail ISP's (hotmail, yahoo, etc.) do all kinds of checks on hostnames (PTR), etc... and we want to make sure that we aren't hurting ourselves in anyway by using an "empty" domain name that we own as our hostname's and nameserver's domain name.

    For instance, if we send mail from the abcd.com account, it will use mail.abcd.com (1.1.1.1) as it's outgoing mail server... Hotmail will see this... do a reverse-dns lookup on 1.1.1.1 and see host.unuseddomain.com. See what I'm saying? It all will work, but will it toss up red flags?

    Thank you for any help!
    Last edited by apacheMan; 03-31-2008 at 02:24 PM.

  2. #2
    Join Date
    Nov 2001
    Location
    Ashburn, VA
    Posts
    1,206
    You can use any hostname/domain name you want on a server. The hostname has no effect on what domains are actually hosted on the server. As long as abcd.com ppoints to the proper DNS servers, it really doesn't matter.

    As for the mail question. This also goes back to DNS. Whatever the MX record(s) are pointing to needs to be configured correctly to handle the mail. You need forward and reverse DNS entries for the host, and the mail server needs to be configured as that hostname. As a rule of thumb, if I have a mail server or DNS server running on an IP, then I configure that IP's reverse record to be the mail server or nameserver. Do you really need a reverse entry for someserver.unuseddomain.com?
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  3. #3
    Join Date
    Jan 2008
    Posts
    42
    Hey serve-you..

    Thank you for the very informative response. If you wouldn't mind, I'd like to follow up with you with a few questions, kind of pick your brain a little more, and get a better understanding of what you are recommending here so I can implement it correctly.

    The new dedicated server I am getting is a Linux/cPanel server with 6 ip's. 1 IP is the main (or shared) IP, and the other 5 are dedicated IP's. Since this is a managed host I am with, I'm not sure how they will initially setup the MX record for my mail.

    When you say, "the mail server needs to be configured as the hostname". As per my want of using host.unuseddomain.com as my hostname for this server... do you mean that my mail server should be host.unuseddomain.com? And in the in-addr.arpa zone file, for whatever the shared IP's last octect is have a PTR record pointing to 'host.unuseddomain.com.' (which is essentially both mail server and hostname)?

    I just want to make sure I read you correctly... I want to take advantage of your advice and implement your suggestions correctly. Thank you so much for your guidance.

  4. #4
    Join Date
    Nov 2001
    Location
    Ashburn, VA
    Posts
    1,206
    That's correct. You could use host.unuseddomain.com as your hostname and setup your mail server using this. Or you could use another IP and assign it something like mail.unuseddomain.com and bind your mail service to that. With a control panel however, it's just gonna use whatever the primary IP/hostname is for the mail server config. It's really just a matter of preference. Your headers of all mail sent from this domain are going to state this hostname. Other than that, it really doesn't matter at all what it is, As long as you forward and reverse DNS match.
    Affordable web hosting, design, & domain registration services since 2001
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  5. #5
    Join Date
    Mar 2008
    Posts
    47
    You should also make sure that your hostname host.unuseddomain.com points to your main server IP address and the main server IP address points (has a reverse DNS record) back to your hostname since some mail servers reject e-mails if they were sent from the server which main server IP and server hostname do not point to each other.

  6. #6
    Join Date
    Jan 2008
    Posts
    42
    Quote Originally Posted by serve-you View Post
    That's correct. You could use host.unuseddomain.com as your hostname and setup your mail server using this. Or you could use another IP and assign it something like mail.unuseddomain.com and bind your mail service to that. With a control panel however, it's just gonna use whatever the primary IP/hostname is for the mail server config. It's really just a matter of preference. Your headers of all mail sent from this domain are going to state this hostname. Other than that, it really doesn't matter at all what it is, As long as you forward and reverse DNS match.
    Hey serve-you... just thought I would confirm with you what I will request of my server/mail configuration per your recommendations. Just a quick summary of situation below...

    Setting up new dedicated server for a website, abcd.com, which sends out mail to users and it is of upmost importance that mail sent out from the abcd.com email addresses have the highest in email deliverability.

    I own the domain name 'unuseddomain.com' and will setup this new dedicated server to be host.unuseddomain.com. I will request that the mail server name to be host.unuseddomain.com (as opposed to the standard mail.abcd.com or mail.unuseddomain.com). Therefore the SMTP Greeting and HELO in all mail headers will show host.unuseddomain.com. I will also setup my custom nameservers to be ns1.unuseddomain.com and ns2.unuseddomain.com and point unuseddomain.com from my registrar to the server.

    I will setup a PTR record in the in-addr.arpa reverse-map zone file for the last octet of whatever my shared IP is, pointing back to host.unuseddomain.com. This will allow proper rDNS lookups for ESP's like Hotmail.

    ..

    Now with this setup.. for the very best chance of email deliverability, would it be wise for me to have abcd.com reside on the shared IP of the server (as opposed to putting it on one of the dedicated IP's)?? That way, the abcd.com domain shares the same IP address as the mail server. Or does this not make one difference whatsoever in terms of email deliverability?

    Thank you so much for all your help. I really appreciate it. Let me know if I misunderstood anything.

  7. #7
    Join Date
    Mar 2008
    Posts
    47
    Quote Originally Posted by apacheMan View Post
    Now with this setup.. for the very best chance of email deliverability, would it be wise for me to have abcd.com reside on the shared IP of the server (as opposed to putting it on one of the dedicated IP's)?? That way, the abcd.com domain shares the same IP address as the mail server. Or does this not make one difference whatsoever in terms of email deliverability?
    It doesn't matter if you point it to the main shared IP address or to a dedicated IP address because Exim is configured to send e-mails from the main server IP address which has a PTR record setup.
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