Forum Discussion

Iron Contributor

Mar 25, 2025

Exchange 2019 SMTP Relay Issue After Adding New Server to Send Connector

I have an Exchange environment with two Exchange 2019 servers — one on-premises (EX01) and the other recently deployed in an Azure VM (EX02). The goal is to eventually decommission the old on-premise...

Iron Contributor

Mar 26, 2025

binodmaharjan_2020 KonstaUPMAppreciate the prompt response guys. Apparently the customer is on a Enterprise Agreement so that's something not affecting.

KonstaUPM

Copper Contributor

Mar 27, 2025

That's good, but they still need to request port 25 being open on selected subscription. So port is blocked for all subscriptions, but only Enterprise customers can request it to be unblocked on selected subs.

Curious_Kevin16
Iron Contributor
Mar 28, 2025
KonstaUPM Thanks for that extra bit there mate. What could we use in this case to test it out properly to see whether its actually open or closed?

Thanks again!
- binodmaharjan_2020
  Copper Contributor
  Mar 31, 2025
  Curious_Kevin16, as we already mentioned, SMTP port 25 is blocked by Microsoft. You need to submit a request if you have an eligible subscription. However, if you want to confirm whether the port is open or closed, you can use various port checker tools available online. For example, you can use:
  https://canyouseeme.org/
  https://portchecker.co/
- KonstaUPM
  Copper Contributor
  Mar 31, 2025
  Hi, basic port query tool should work. But I am 99% confident that it is Azure blocking your traffic.