Share invite not sending to all recipients

Hi Everyone!

I've run into a problem where I'm trying to share a folder with 6 of my collegues and it works great for all but 1 of them.   The person in question has never recieved an email with the invite.   We're all on the same work network so I doubt it's being filtered out if it works for everyone else.

Has anyone run into a problem like this?   Not really sure where to begin trouble shooting it!

Thanks for help.
-Greg