Additional chat-related features and issues within Microsoft Teams for Education
Dear Kevin,
As an Independent Advisor and community user, I'll help you with your question.
At this point as a final user there his no way to block other users, so, in order to block other users you have to talk with the Teams administrator, they can to block domains with a Teams policy.
By other hand, if you concerned about block contact in Teams, it is recommended to vote in this suggestion at https://microsoftteams.uservoice.com/forums/555... and leave your good ideas there. Microsoft will keep monitoring customers feedback and good ideas there, some features would be added into the product and services based on customers feedback in the future, and your good ideas will be very helpful for the dedicated develop engineers in Microsoft to improve their product and services.
Regards,
Renzo.