This doesn't look like a valid user ID. Make sure you typed the user ID assigned to you by your organization. It usually looks like firstname.lastname@example.org or email@example.com.
This situation can occur if the user's UPN changed but directory synchronization didn't yet occur to sync the change.
For more information about how to troubleshoot UPN suffixes, go to the following Microsoft Knowledge Base article:
Article ID: 2844931 - Last Review: Dec 20, 2016 - Revision: 1