Add members to Teams without Welcome Messages

When you add someone to Teams, the recipients get a welcome message by Microsoft. In some situations, you might to suppress this default behavior by changing the setting at the Teams level.  

To DISABLE the welcome message, just use this parameter on the individual Teams or Unified Group " UnifiedGroupWelcomeMessageEnable"

You'd need to be connected to Exchange Online module via PowerShell for it to work.

Set-UnifiedGroup -Identity "Name of your Team or Group" -UnifiedGroupWelcomeMessageEnable:$false

Example - 

Set-UnifiedGroup -Identity "TEST Team1" -UnifiedGroupWelcomeMessageEnable:$false

If you want to restore the welcome email functionality, just set it to $True again.

Example: 

Set-UnifiedGroup -Identity "TEST Team1" -UnifiedGroupWelcomeMessageEnable:$true