Exchange 2010 Hybrid --> Exchange 2016 Hybrid

Brass Contributor

Hi All,

I am trying to finish off an upgrade to our on-prem stuff. We are an O365 shop, but have kept an Exchange 2010 hybrid on-prem for some email management activities and to be an SMTP relay for internal applications that send email to employees, customers, etc.

I have the Exchange 2016 server installed, have copied the SL cert from the 2010, updated SCPs, migrated arbitration mailboxes, updated internal DNS, configured an appropriate receive connector on the 2016 (for internal application SMTP relay), and have added the 2016 server as a "Source Server" on the existing send connectors (outbound to Internet, outbound to O365), etc.

Stuff is working ok for the most part - though we are getting some comments from employees and customers that email is getting stuck in Quarantine. While there may be a correlation there - and I need to figure that out - my first concern is getting the upgrade finished and the 2010 server shut down.

So... the last thing for that I think is running the HCW. 

Our current hybrid config I believe is a full hybrid config (heck, it was created back in like 2012 when we migrated all mailboxes to Exchange Online). So, I assume that I should do the same with the 2016 HCW? What is throwing me for a loop is that I was under the impression that the HCW would detect our current config and just "upgrade it" (per this article). This does not seem to be the case, and the HCW is asking me if I want a minimal hybrid config or a full hybrid config. At this point, the minimal sounds like it would be more appropriate for us - we are not creating any on-premise mailboxes anymore.  However, I don't know if that will break any mailflow for us - specifically using the "outbound to O365" send connector that was (as far as I know) created when the hybrid config was established in 2012.

I haven't the ooportunity to try this out in a lab / test environment, so I just want to make sure that I don't send anything into the wonk...

Any advice would be greatly appreciated!

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