Disabling Centralised Transport

Question

Disabling Centralised Transport

Mike00 241

Hi,

We are almost at the point where our Exchange migration to Exchange Online are complete ( a few mailboxes that will remain on-premises). We are looking to move the email routing dependency off of the on-premises infrastructure and route in/outbound email directly to/from Exchange Online via our third party cloud mail filtering solution.

Currently we have centralised transport enabled and I have to disable it prior to configuring inbound/outbound email to go direct. The outbound connector used to route internet and on-premises email is currently configured as below:

Enabled : True
UseMXRecord : False
Comment :
ConnectorType : OnPremises
ConnectorSource : AdminUI
RecipientDomains : {*}
SmartHosts : {on-premhybridendpoint.domain.com}
TlsDomain : hybrid.domain.com
TlsSettings : DomainValidation
IsTransportRuleScoped : False
RouteAllMessagesViaOnPremises : True
CloudServicesMailEnabled : True
AllAcceptedDomains : False
SenderRewritingEnabled : False
TestMode : False
ValidationRecipients : {}
IsValidated : False
LastValidationTimestamp :
AdminDisplayName :
Name : Outbound to {GUID}
DistinguishedName : CN=Outbound to {GUID}
Identity : Outbound to {GUID}

I am planning on updaing mail routing in three phases:

Phase 1: Set "RouteAllMessagesViaOnPremises" property to $false to disable centralised transport ( assuming all email sent from EOL senders will still route via on-premises infrastructure after this until I create the new Outbound connector to route to the internet directly based on the fact that the recipient domains on the connector will still be *)?

Phase 2: Create a new send connector to route email destined for internet recipients (*) to route out directly from EOL and configure the Outbound connector above to route on-premises only for "AllAcceptedDomains" instead of *

Phase 3: Create a new inbound connector to accept email from in-line mail filtering appliance and cutover email destined for our company domains direct to Exchange Online.

Is anyone able to confirm if anything else needs to be considered here or if I have missed anything?

Mike

Richard McDonald 0 Reputation points

2023-06-15T19:08:34.22+00:00
I am planning to this as well without running HCW, I think besides setting the outbound connector RouteAllMessagesViaOnPremises to $false, I think I also need to adjust the Hybrid Configuration on-prem as well and set the same features with excluding CentrailizedTransport

Get-HybridConfiguration | fl features Features : {FreeBusy, MoveMailbox, Mailtips, MessageTracking, OwaRedirection, OnlineArchive, SecureMail, CentralizedTransport, Photos} Set-HybridConfiguration -Features FreeBusy,MoveMailbox,Mailtips,MessageTracking,OwaRedirection,OnlineArchive,SecureMail,Photos

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Richard McDonald 0 Reputation points

2023-06-15T19:08:34.22+00:00

I am planning to this as well without running HCW, I think besides setting the outbound connector RouteAllMessagesViaOnPremises to $false, I think I also need to adjust the Hybrid Configuration on-prem as well and set the same features with excluding CentrailizedTransport

Get-HybridConfiguration | fl features Features : {FreeBusy, MoveMailbox, Mailtips, MessageTracking, OwaRedirection, OnlineArchive, SecureMail, CentralizedTransport, Photos} Set-HybridConfiguration -Features FreeBusy,MoveMailbox,Mailtips,MessageTracking,OwaRedirection,OnlineArchive,SecureMail,Photos

Answer 1

Yuki Sun-MSFT 41,456 Moderator

Hi @Mike00 ，

Currently we have centralised transport enabled and I have to disable it prior to configuring inbound/outbound email to go direct.

Theoretically it should be supported to disable centralized mail transport manually by modifying the connectors involved. But based on my research, there's no official document explictly stating the detailed steps. So I'd like to recommend disabling the centralized transport by rerunning the HCW and unselecting the checkbox of "Enable centralized mail transport", it will take care of the rest and update your outbound connector settings:

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Mike00 241 Reputation points

2021-08-25T21:27:26.987+00:00

Hi YukiSun,

Thanks for the response, however I am trying to avoid running the Hybrid wizard again as it will force all outbound email to go directly from Exchange Online which I do not want to do immediately.

IAlso we have some customised configuration in Exchange Online and on-premises and if I run the Hybrid Wizard again it will reset all of the configuration.

Mike.
Yuki Sun-MSFT 41,456 Reputation points Moderator

2021-08-30T07:41:12.693+00:00

Hi @Mike00 ，

Re-running HCW will configure your on-premises Exchange and Exchange Online organization for hybrid mail routing by configuring new and existing connectors in the on-premises organization and Exchange Online. It's the recommended way to disable the centralized transport. If you still prefer re-configuring it manually, considering that there's no official guide for it, I'd suggest doing it in non-working hours to mitigate the user impact in case it doesn't work as expected.

Besides, regarding the "Phase 3: Create a new inbound connector to accept email from in-line mail filtering appliance...", below is a document about useing a third-party cloud service for spam, malware, and phish filtering with Exchange Online, hopefully you can find it be of some help:
Manage mail flow using a third-party cloud service with Exchange Online

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Nadeem SURFALY 0 Reputation points

2023-04-11T06:30:35.2966667+00:00

Hi there. I had the same issue and an internet search turned up this page. Centralized mail transport was enabled at first in our hybrid setup and later on, it had to be disabled. I can confirm that running the hybrid configuration wizard and unchecking the option "Enable centralized mail transport" performed the necessary updates and now Office 365 takes care of external email routing. Thank you Yuki Sun.

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Disabling Centralised Transport

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