Leave copy of email on server...

With a POP account, the iPhone's email client includes an account preference setting to not delete messages from the server when downloaded by the account which should be all that is required which is the same for every other email client on the planet.

Are you saying this is not working for your POP account?

A POP account is not designed to be accessed with an email client on multiple computers or devices - it is designed to be accessed with a single email client only.

mbiphone,

The iPhone leaves messages on the server by default.

Outlook and Outlook Express do not.

And it is the same setting, just worded differently. Delete from the server tells it when to remove it. If you set it to never, that means the iPhone will not remove it from the server. It is the same setting, but with more control.

If you want to have the status of the message synced to the server IMAP supports this, and has a longer track record than MAPI.

Hope this helps,

Nathan C.

NOTE: Google using POP3 and some other POP3 servers may remove them from the mailbox after it has been downloaded by one mail client, that is a server side setting. For Google you just need to add recent: before you user name to prevent that. However, you will get copies of your sent messages when using recent: This article in Google's Help section has more about it with GMail:
http://mail.google.com/support/bin/answer.py?answer=47948

IMAP is better suited for what you want.