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exchange connecting to wrong email server

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  • exchange connecting to wrong email server

    i setup a microsoft small business server 2003 using network solutions for dns hosting. i enabled smtp logging because of this problem, incoming email to our domain has no problems. i could also email tons of other domains no problem as well.
    it seems like when my domain emails a domain that uses appriver or mxlogic as their spam provider emails intermittently bounce. i found a pattern of the problem in my smtp log. anytime our server connects to their website IP (which it shouldn't in the first place right?) email bounces back with User Unknown or Relaying Denied non delivery reports. (of course it will bounce back because the user probably doesn't exist or that mail server could be running but not accepting mail.) why would it connect to their website IP and not their MX record IP? my exchange server looks up another domains email server by mx records right? it can't get it wrong can it?

    if it connects to their spam provider first then mail gets delivered ok. the IP of domains that i get the bounced mail from i could telnet into port 25 and it responds back as a mail server of some sort... it could be their old server but why would our exchange server connect to their old website/mail server instead of their new mail server/MX record?

    is this a problem with my mail server or do they have outdated dns or mx records somewhere?

  • #2
    Re: exchange connecting to wrong email server

    Have you verified that the domains in question have valid MX records. An SMTP server can't "connect" to a web server as they run on different ports. Your email server is only capable of connecting to port 25 on other email servers. The NDR's that you are getting are definitely coming from an SMTP server. The way email works is that an SMTP server will query for an MX record and if it can't find one it will look for an A record for the domain in question. Many companies set up A records for their domain and then set up web sites on the same host that the A record points to, so it looks like your server is connectiong to a web server but it isn't it's connecting to the A record that it found because it couldn't find an MX record. Run nslookup from your SMTP server for the domains in question and see if it can find the MX records. What are the domains in question?