Migration from cisco IronPort Centrilized mail flow to Microsoft EOP

Question

Hi Experts, Currently we have Centralized mail flow and using Cisco Iron port for sending and receiving the messages. Around 85% mailboxes are already in cloud but still we are using Iron port as a centralized mail transport. We have lot of accepted domain where Iron port is receiving the messages. Now we are planning to transition from Iron port to EOP. Please let me know the best approach to do so, Regards AM

Answer 1

1. Ensure all the accepted domains are in Exo : https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-accepted-domains/manage-accepted-domains
2. Ensure the MX record is set correctly for all those domains
3. Re-Run the Hybrid Wizard and choose regular transport, - not centralized.

You could do all this manually as well to disable centralized mail flow,however this is where the Wizard is handy

https://www.reddit.com/r/exchangeserver/comments/9h66yz/centralized_transport_removal/

Also make sure:
https://learn.microsoft.com/en-us/exchange/transport-options

Answer 2

@RJ

Whether following information correctly?

1. Do you using a hybrid environment?
2. 85% mailboxes hosted on Exchange online and 15% mailboxes hosted on Exchange on-premises
3. Using IronPort to filter email for Exchange on-premises?

If you want to using the EOP are incoming point, you need verify all needed domains in Office 365 admin center, then change MX records from IronPort to EOP.

The centralized mail transport effect in hybrid, you can have a look about this article: Route incoming Internet messages through the Exchange Online organization If you want to disable it, you could disable it with rerun HCW as AndyDavid said.

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Answer 3

Why cannot we use Ironport and EOP together in mail workflow.