Exchange Public Folder to EXO migration issue
Posted by Rough_Crack@reddit | sysadmin | View on Reddit | 3 comments
Running into a stubborn issue with an Exchange 2016 - Exchange Online Public Folder migration and looking for some sanity checks.
Environment:
- Exchange 2016 (on-prem, hybrid configured)
- \~770 GB Public Folder data
- Using native Microsoft PF migration (MRS over EWS)
- EXO migration endpoint configured
- MRSProxy enabled and externally published
Problem:
Test-MigrationServerAvailability -PublicFolder consistently fails with timeout to:
https://mail..com/EWS/mrsproxy.svc
Error:
"The HTTP request to mrsproxy.svc has exceeded the allotted timeout"
So far:
- Credentials are valid (on-prem Exchange admin)
- Endpoint resolves and is reachable on 443
- Behavior changes depending on firewall rules
Network team is pushing to whitelist Microsoft 365 IP ranges instead of allowing open 443 access to the VIP. From what I understand, M365 uses dynamic backend IPs and this may not be reliable.
Has anyone successfully locked down PF migration traffic to M365 IP ranges without breaking MRS?
Is SSL inspection known to consistently break MRSProxy (seems likely here)?
Any gotchas specific to FortiGate / reverse proxy setups for this scenario?
Anything else besides firewall that could cause mrsproxy timeouts like this?
Trying to avoid kicking off a multi- day migration only to have it fail mid- stream.
Appreciate any help!!!
7amitsingh7@reddit
Having 770 GB in Public Folders is unusually large and Microsoft has been moving away from them in favor of newer options, in real-world scenarios many organizations still depend on them, so migration is often unavoidable. Moving Public Folders from Exchange 2016 to Exchange Online is possible but can be slow and complex at that size, so it’s worth considering long-term alternatives like SharePoint or shared mailboxes but if business needs require it, proceed with migration while planning a future cleanup or redesign.
kvorythix@reddit
that's brutal. tax-deadline week is exactly when mail breaks the worst, of course
Ultron_Magnus@reddit
You should probably be asking why a public folder has this much data and why can't it be moved to a share or somewhere else rather than wasting time trying to move it when Microsoft has continuously been phasing out support for public folders.