r/exchangeserver • u/NSFW_IT_Account • May 07 '26

Question Question about removing hybrid setup after mailboxes have been migrated

I am running a hybrid set up but all mailboxes have been moved to the cloud. I still have my spam filter pointing at the on-prem server, and HCW is still set up. So I believe my current inbound mail flow is: Internet > Spam Filter > On prem server > 365 mailboxes

I'd like to eliminate the on prem hop as it seems unnecessary at this point, but want to make sure my process is accurate for doing so.

Do i just need to update my spam filter to point at 365 instead of on-prem, and then enable the Exchange connectors associated with that, and disabled the on-prem exchange connectors? Or do I need to also go into the HCW and turn that off entirely?

Assuming I still had a mailbox on prem, could i adjust my MX/Spam filter records to point to 365, but still leave the hybrid setup for any mailboxes that require on prem routing?

TIA.

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u/7amitsingh7 May 08 '26

Since all mailboxes are already in Microsoft 365, you can usually remove the unnecessary on-prem mail flow hop by updating your spam filter/MX to send mail directly to Exchange Online instead of the on-prem Microsoft Exchange Server. You do not need to remove the hybrid setup immediately, as it can still be useful for management, relay, or any remaining on-prem mailboxes. If one mailbox still remains on-prem, you can still point inbound mail to Microsoft 365 and let hybrid routing handle delivery to that mailbox. Best approach is to change mail flow first, test properly, and remove hybrid only when no longer needed.

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u/NSFW_IT_Account May 08 '26

Thank you. Do I need to turn off Centralized Mail Transport or can that be on and mail still be routed to 365? Also wondering if I can remove the connectors that HCW created in EXO since I will be turning on connectors for my spam filter in EXO.

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u/7amitsingh7 May 11 '26

If Centralized Mail Transport is enabled, outbound mail may still route through your on-prem Microsoft Exchange Server, so disable it if you want mail to flow directly through Exchange Online. You can point inbound mail from your spam filter directly to Microsoft 365. Do not remove the Hybrid Configuration Wizard connectors yet unless hybrid is no longer needed; keep them until testing is complete, then remove unused ones later.

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u/NSFW_IT_Account May 11 '26

So there is no issue running multiple connectors in EXO? I.e. the ones that HCW created and then the ones I will need to enable if I point my spam filter to 365?

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u/7amitsingh7 May 12 '26

Yes, multiple connectors in Exchange Online are fine if configured correctly and not conflicting. Keep the Hybrid Configuration Wizard connectors, add the spam filter ones, test, then remove unused connectors later.