Group Email invitations are not being received by some

scardinal

A professor is inviting her students to a new shared group, something that she has often done. This time only some of the students have received invitations to the group. Missing emails were not found in spam or misrouted to other folders. She is contacting our IT Department. Any ideas why this might happen? I shared with her that Microsoft was having issues - those seem to be resolved. Anyone else have this issue recently?