At the recent Microsoft Ignite conference my friend and fellow MVP Michael Van Horenbeeck delivered a short presentation titled Edge Transport servers and Hybrid: Why, or why not?
You can check out the slide deck here, but to summarize the main points, the reasons to run Edge in a hybrid environment are:
- You have a technical/security requirement to terminate incoming SMTP (from Exchange Online) in your DMZ
- You need to re-route messages before they enter your on-premises Exchange organization
- You need the Edge Transport server's address rewriting capabilities
The reasons not to deploy Edge are:
- You have more servers to manage
- Edge Transport mail filter (e.g. anti-spam) features are not as effective as other solutions
- It increases the complexity to your environment
Michael also notes that managing Edge Transport is PowerShell only, which may be a downside for some admins.
I happened to be running an Edge Transport server in my hybrid test lab, and hadn't really thought about whether I needed it until I saw the tweets during Michael's presentation. Originally I deployed the Edge Transport server in my lab to route email to some separate labs on different domains. Occasionally my lab's mail flow would break, and I had to deal with the added complexity of troubleshooting an environment that has an Edge server deployed. So I decided to get rid of it.
Removing an Edge Transport server from a hybrid environment is not a difficult task in itself, but you might have environmental factors that increase the work involved. The steps I followed were:
- Re-run the Hybrid Configuration Wizard to reconfigure my hybrid mail flow to use the Exchange 2016 Mailbox servers, instead of the Edge Transport server.
- Updated my inbound NAT for SMTP (TCP port 25) to point to the Exchange 2016 Mailbox server (I made this change immediately after running the HCW).
- Sent some test messages and waited 24 hours, then confirmed with message tracking logs on the Edge Transport server that no new messages had traversed the Edge server.
- Removed the Edge subscriptions.
- Uninstalled the Edge Transport server.
- Shut down and decommissioned the VM.
The result is a simpler Exchange hybrid environment with fewer servers to operate, maintain, and troubleshoot.