Forum Discussion
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-premises server.
We use a receive connector for SMTP relay from MFPs (printers) and applications to send scanned documents to internal users (all mailboxes are hosted in Microsoft 365). I've replicated the receive connector on the new server (EX02) with identical settings, including the public certificate. All necessary ports are open, and the configuration matches the old server (anonymous relay).
However, when I add EX02 to the send connector and test email relays from scanners or apps, the messages are never delivered — they seem to disappear entirely. No NDRs are generated, and nothing shows up in the queues or logs indicating a failure.
Interestingly, the new server does receive the relay messages — I can see its hostname in the message headers for successfully delivered emails (prior to adding EX02 to the send connector), so it's definitely accepting the relay connection but something is wrong on the sending.
I haven’t run the Hybrid Configuration Wizard on either server, as these servers are only used for SMTP relay purposes.
Any idea what I might be missing? What could be causing this mail transport issue on the new server?
Much appreciate your ideas !! Thank you
7 Replies
binodmaharjan_2020KonstaUPMAppreciate the prompt response guys. Apparently the customer is on a Enterprise Agreement so that's something not affecting.
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.
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!
Hi Curious_Kevin16,
If I am not wrong, your query is that after adding the Exchange Server on an Azure VM, SMTP was not working, right? This might be due to outbound SMTP connectivity issues in Azure.
In an Azure subscription, for Enterprise Dev/Test subscriptions, port 25 is blocked by default. To allow SMTP from an Azure VM, you need a standard Enterprise Agreement or a Microsoft Customer Agreement for Enterprise (MCA-E) subscription.
Wild shot, but. Azure will block any outgoing connections on port 25. https://learn.microsoft.com/en-us/azure/virtual-network/troubleshoot-outbound-smtp-connectivity
