The problem we wish to resolve is failed Reverse SMTP banner lookups.

  • Publicly we have one IP with a single host name and MX record: mail.domain.com
  • Internally we have 6 servers that send out that same one public IP address
  • All our internal servers have the default SMTP sending banner, which means they display "server#.internaldomain.lan" to the external recipient domain.

And so the questions/solutions:

  • Can we set the FQDN in the SMTP sending gateway for all servers to be the same mail.domain.com and continue just using the one IP? Will this open other issues/problems?
  • Or must we set each server to use a unique public IP, and set their respective FQDN. eg serv1/ip1, serv2/ip2 serv3/ip3...?
  • Or must we setup a dedicated mail gateway(smarthost) with the proper SMTP banner.?
  • How is your Exchange environment set up? As is, is one of your mail servers designated as an Edge Transport server? I'd think that would be the "best practice" for Exchange 2010. – HopelessN00b Jul 20 '12 at 22:44

It's perfectly OK to set the FQDN on every server to mail.domain.com and continue to use the one IP.

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