Give the ability to disable the "You're now a member of group" email.
The WelcomeMessageEnabled attribute already exist, allow us to change it. We are migrating existing groups and our users already know they are in those groups and when several users are in over 30 different groups I don't want to SPAM them. Also we have groups based on region and don't really want to send an email to everyone in those regions when we create the groups.
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.
Matt Gudites commented
Good but not enough. You need to provide a way to disable this altogether when creating a group. It's unacceptable that Microsoft would think it okay to send out a notification to a large group, created by an Azure Admin no less, with no warning. Stop trying to think so ******* behalf of enterprise organizations.
I lost my job because of this hidden feature in Azure dynamic lists which sent out thousands of emails with no warning. It’s 2020!
Brian Grider, you don't need to put the name of each individual group in your mail flow rule... just put "You're now a member of the" but also you will need to add another rule that filter the "joined the group" because there are two different welcoming messages, one from the Exchange Admin and one when a member is included from Outlook...
I learned in a hard way...
Looks like it's available via powershell now. See https://techcommunity.microsoft.com/t5/Office-365-Groups/How-to-remove-the-Welcome-Message-when-a-new-member-joins-a/td-p/56573
William Yi commented
John Utley commented
I don't know how they haven't allowed the WelcomeMessageEnabled parameter to be changed yet. We are setting up a lot of new groups for a new software we are going to use, but we don't want to send out the instructions for using the software and the reasoning for using the groups until after the groups are created and everyone is added to the appropriate groups. I'm already getting calls and emails from staff asking why they were added to this new group and it's making it difficult to complete the project because I'm getting all these calls and emails.
Bryan Grider commented
Note that a work around for right now is to create a Mail Flow rule to delete message when the body/subject contains the phrase "You're now a member of the **** group". But this is tedious when migrating over 200 groups.