To summarize, I have a client where some of their users are getting duplicate emails intermittently from both Internal and External senders.
I have fixed one of the users from getting duplicate emails by turning off the feature that says to leave email on the server for X amount of days. Once I turned this off and deleted all the duplicate emails in her inbox, the problem went away.
I thought I could use this method to solve all of the users problems but ran into the fact that many users have their iPhones that also connect to the email server. As far as I know, this requires the email to be left on the server so the iPhone can download the email also.
It is almost like there is some flag that is supposed to be set on the email server that tells Outlook it has already downloaded that email, but Outlook is re downloading the email every time it polls the POP3 / SMTP mail server.
When the email is duplicated, it always shows the exact same Received time.
The email server is a server called SurgeMail. It is simply a generic POP3 / SMTP server with Webmail access. Any ideas would be greatly appreciated.