Mail Duplication on Client side(Outlook and LiveMail)

[damith]

Dear All,


I'm running Zimbra mail server(8.8.11_GA_3772.FOSS) and my users are used 3rd party mail client(Outlook and LiveMail) to send and receive emails. Many of their emails are duplicated. I havent any idea for how this was happening. Please guide me to resolve this issue.

Thanks