Scenario
You have a hybrid mail flow environment with mailboxes both on-premises and in Exchange Online (Microsoft 365). You want to know how best to configure Exclaimer for this scenario.
Note: If you have centralized mail flow and use Server-Side signatures, it is recommended that you also see the solution: How to set up Exclaimer in a hybrid environment using centralized mail transport.
Resolution
There are different recommendations for Client-Side and Server-Side signatures.
Client-side
To apply Client-Side signatures for users Exchange Online mailboxes, use the Outlook Add-In.
To apply Client-Side signatures to on-premises mailboxes, use the Exclaimer Signature Update Agent.
To apply Client-Side signatures to on-premises mailboxes, use the Exclaimer Signature Update Agent.
Warning: The Exclaimer Outlook Add-in is only supported for Exchange Online mailboxes.
Server-side
When you have mailboxes both on-premises and in Exchange Online, run the Exchange On-Premises setup, then the Connect to Microsoft 365 setup.
- Complete the steps for Connect to Microsoft 365.
This will allow for any emails routed through Exchange Online to have a signature applied. - Complete the steps for Exchange On-Premises.
This will allow any emails that remain on-premises or route directly out to the internet from the on-premises server to have a signature applied.