Scenario
After running the initial connector setup for Exclaimer Cloud, the user’s email addresses have changed to use the .onmicrosoft.com domain associated with your Microsoft 365 subscription.
Reason
Microsoft has confirmed that this occurs when the data is synchronized from an on-premises Active Directory to Microsoft 365/Azure AD, and the proxyAddresses attribute for users are not populated in the on-premises Active Directory.
Resolution
The proxyAddresses need to be populated with the relevant SMTP addresses for the users.
The format of the data for the user's primary SMTP email address should be:
SMTP:primary.email@yourdomain.com
The format of the data for any alias email addresses should be:
smtp:alias.email@yourdomain.com
Microsoft has provided the following PowerShell script to set the proxy address for a list of users stored in a CSV file:
foreach($user in $users)
{ $u = Get-ADUser $user.name -Properties mail,department,ProxyAddresses $u.ProxyAddresses = $user.ProxyAddress Set-ADUser -instance $u }