How to Disable Welcome message to group Office 365 online(Azure Directory)?
Solution 1:
Using PowerShell
Step 1 Open PowerSheel and connect to ExchangeOnline

PS C:\Users\UKgoodByeSales> Connect-ExchangeOnline

Step 2 Change the value of this UnifiedGroupWelcomeMessageEnable to “false”

PS C:\Users\UKgoodByeSales> Set-UnifiedGroup -Identity "UKgoodbyeSalesDepartment@groups.ukgoodbye.co.uk" -UnifiedGroupWelcomeMessageEnable:$false

Use the command Get-UnifiedGroup view the variable of the Sharepoint group or Azure D group:

C:\Users\MoussaSow> Get-UnifiedGroup -Identity "UKgoodbyeSalesDepartment@groups.ukgoodbye.co.uk" | Format-List