Enable external emails for @mentions
If your company does not use Outlook emails with Office 365, @mention-style notifications are not an option. Without this, it's extremely hard to productively collaborate around a doc. All the other software we use associates emails with user profiles to make this a possibility.
Extremely needed to be able to assign and follow up tasks for internal and customer project members. Otherwise we need to go back to the use of email for customer team members, while using @mention for internal team members. This is inefficient and time consuming. If it is allowed to have guests in a tenant, it should be possible to collaborate with them as well
+1 We do use Outlook emails but we have external users. Not having the ability to @mention them is a disadvantage.