Score:0

Inbound SMTP not working

ua flag

I am in the process of deploying and configuring an on-premise exchange 2016 server. My inbound/receive connector is not working. When I telnet into my server on port 25 from a computer on an external network, I get:

220 Row3Exch.Slowservers.com Microsoft ESMTP MAIL Service ready at Mon, 25 Oct 2021 16:57:57 -0400

However, I am unable to receive emails. I ran the inbound connectivity analyzer to see if there was something that I am missing. The results say that port 25 is blocked, not listening, or producing the expected response. Looking at my DNS records and my telnet results I am a bit confused on what it can be. Here is a screenshot of the results

joeqwerty avatar
cv flag
Your external telnet test confirms that your server is reachable via port 25. It seems to me that your MX records are probably misconfigured. Right now they point to mx1.forwardemail.net and mx2.forwardemail.net.
Jacob Harrand avatar
ua flag
You probably looked at it when my coworker was trying a forwarding program to forward emails temporarily
Score:0
ua flag

I figured it out. It has nothing to do with the exchange setup. On our firewall I have my external address on a white-list for SMTP. Removing the white-list and allowing all traffic solved the problem.

Joy Zhang avatar
us flag
Glad that you have resolved this issue, you could mark the solution as best answer if someone encounters the same issue, they could find the solution quickly:)
Score:0
us flag

I want to confirm if you can receive mails from internal?

According to the error messages, here's a solution provided in a blog to resolve the issue: restart Microsoft Exchange Frontend Transport service. Then you could check if this issue continues.

If above solution cannot work for you, here are some troubleshooting steps for your reference as well:

  1. Could you check the configurations of DNS records? enter image description here Then you could follow this guidance to check the Public DNS records: Check the Public DNS records

  2. In addition, is there a firewall in your environment? If so, you also need to check the firewall configuration.

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