We are running ms exchange 2013. we have only 15 email users. All email users are sending and receiving emails perfectly. Only two of my users (John@example.com and Shirley@example.com) are having issues. 6 days ago they stopped receiving incoming emails both internally and externally but they are able to send emails out perfectly.
Just a day a go i found out that both John and Shirley's emails have been going to another users (firstname.lastname@example.org) inbox. Now wonder they themselves haven't been receiving incoming emails.
I checked both users outlook client accounts but there wasn't any rules applied that could have done forwarding. Also i checked through the Outlook Web App (OWA) and same, no emails have been coming through their mail box.
Im not really good at ms exchange. Could there be some forwarding or filtering done through exchange or else where to cause the user mailboxes to forward to another user mailbox?