User's own name apears in CC while replying

When a user try to reply to any internet email her own internet address automatically comes in cc field. She is clicking on Reply to All when this happens. No issues when internal users sends her an email.

I have created a new replica, new copy but no luck, ran maintenance, happening on local n server mailfile

please advise

Subject: Answer

Location document was at fault, it was having the incorrect internet address