Access our public email server from internal network?

Posted on 2006-04-28
Last Modified: 2012-06-27
We are using Netmail for our email, POP/SMTP server. Our users connect to it internally with internal IP, and externally with public IP in outlook. Problem is our mobile users that have Outlook configured to use public IP for POP/SMTP can't connect to email server when they are internally plug in to internal network.
I have a Watchguard x700 firewall.
I need to allow users to connect internally to mail server using our Public IP.

I tried using DNS (eg. but our public dns mail records point to our domain provider and not our public ip.
Question by:dguillen
    LVL 9

    Accepted Solution

    Can you have your ISP setup a RDNS record so that the mail server responds to  That way your users can access it externally and you can have a DNS server internally router the same name to your mail server.  
    LVL 1

    Expert Comment

    actually, I didn't understand your question well,  you have a public IP  of your mail serverconfigured in outlook express and  you want attache this machine to your network internet and want to access mails ? right? you haven't specified much information, I don't know about that particular firewall, but you can probably configure it to route packet to your internal host coming to your public IP.

    check this link for common problems you can probably face.
    LVL 2

    Expert Comment

    The problem is the firewall either doesn't support or has been enabled so that the external IP can be accessed from the internal network. This is called loopback.

    If the firewall doesn't support loopback (contact watchguard) you could use multinetwork manager and set it up so that when you are internal, there is a host name that points to the internal ip, and when your external, that host name points to the external ip. Then use the hostname in the mail settings.

    setup a dns record called with the external ip.
    use this name in outlook
    use MNM so that when you are internal points to the internal ip.

    the host file is stored in c:\windows\system32\drivers\etc.

    you can either use hosts or lmhosts. Both do the same thing except lmhosts has more options for this hosts would be OK.
    LVL 1

    Expert Comment

    He could also write a logon script which can change his/her host/lmhost file at logon time ;)
    LVL 1

    Author Comment

    thanks for all the feedback guys.
    Registering a DNS name for is probably the way to go with this.  Watchguard already told me it doesn't support "loopback" and it won't ever work internally.
    I will try it this week and post results.


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