Recently, it would seem that a client's Zimbra webmail account was hijacked. Now, whenever he uses the Zimbra webmail ZCS to send out, the receiver sees his name differently, and there is a reply-to that is clearly not his email address. This does not happen when he accesses Zimbra via POP or IMAP. I checked his user settings in the Administrator ZCS site and everything looks okay there. I inherited this server from a former admin and am not too familiar with the Debian OS. Any help would be appreciated.