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Multiple IP addresses for MX record?

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  • Multiple IP addresses for MX record?

    We are looking to purchase additional lines to the small office where I work and I was wondering how that would impact our Exchange 2003 installation. They would be from a different provider, so we would have both the T1's coming in to the office off of 1 router, then the additional lines from another company also come in. I know you can have multiple mail servers for one MX record, but can you have multiple IP's for one mail server and if so, where do you set that up? Or would we just sit another router between the 2 managed routers and still router to the same name in the MX record? Sorry if this seems like an easy question but I am new to Exchange Administration.
    Last edited by wssnoob; 20th December 2007, 22:04.

  • #2
    Re: Multiple IP addresses for MX record?

    You can add an additional MX record for your IP address. To do this you'll need DNS access to where ever your DNS is being hosted - Just because you're hosting mail or your company's homepage for their website doesn't mean you're hosting DNS. If you're unsure who's hosting it you should get in touch with someone within your organization who knows. Once you have access to your domain's authoritative DNS start by doing the following. First, add an A record for the new IP, call it whatever you like depending on your interface it will depend on how you add each record, typically this is what you'll need to know,

    [Host, TTL, Record Type, Data]
    (, 60, A,

    then add an additional MX record and point it at the new A record i.e.

    [Host, TTL, Record Type, Prioity# Data]
    (, 1440, MX, 5

    Setting the same priority for both records will cause it give you a pseudo round-robin effect on bandwidth utilization.

    You don't need to do anything within Exchange.

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    • #3
      Re: Multiple IP addresses for MX record?

      When it comes to incoming email, Exchange doesn't care where it comes from.
      However the problem is with outbound email. You cannot have multiple gateways. If you want to run multiple connections you should look for a router that can support multiple WAN connections and let the router sort it out.

      DNS wise, my preference is to use identical information for both connections, with both IP addresses in the DNS. Then have the same reverse DNS entries on both IP addresses. This allows the same FQDN to be used on the SMTP virtual server.

      Simon Butler
      Exchange MVP

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