1,178 votestry this instead · AdminMicrosoft 365 Groups Feedback (Product Owner, Microsoft Office 365) responded
Disabling the welcome mail is possible with an extra parameter in the Set-UnifiedGroup cmdlet in Exchange PowerShell: -UnifiedGroupWelcomeMessageEnabled:$false. See https://docs.microsoft.com/en-us/powershell/module/exchange/users-and-groups/set-unifiedgroup
Use this as a part of a custom group creation flow if you would like to restrict and/or customize the welcome mail for many groups across your tenant.
An error occurred while saving the commentAnonymous commented
A worse situation happened to us. We created a dynamic group for guest users to use for SharePoint permissions, and the welcome email went out to all of them containing a list of members of the group! There needs to be a way to suppress this email just like you can when creating a SharePoint group. In any case, we got around it for future membership changes with a mail rule.