How can i sync email deletions on my iPhone and iMac, and vice versa?

My email provider is Sky in the UK. While i am able to receive the same emails on both devices (imac and iphone) simultaneously, if I delete one on the iphone, it is not deleted on the iMac, and vice versa. I don't want to have to delete emails twice, once on each machine, but rather only once on one machine (and then that email would automatically disappear from the inbox of the other machine).

Is this possible? My sky account is IMAP on the Iphone, but POP on the IMAC. I tried changing it to IMAP on the iMac, but then i couldn't received email messages in MAIL on the iMac so reverted it back to a POP account.

Any advice appreciated. Spent way too many hours today trying to figure this out.

Thanks,

Joe