This decision affects whether your mail survives a lost phone.
IMAP
Mail stays on the server. Your phone, laptop and webmail all show the same folders, the same read status and the same sent items.
Choose this. It is right for almost everyone.
POP3
Mail is downloaded to one device and usually deleted from the server. Other devices never see it.
POP3 made sense when storage was expensive and people used one computer. Today it causes more problems than it solves.
WHY POP3 CAUSES TROUBLE
Mail downloaded to a laptop is invisible on the phone If that laptop fails, the mail is gone unless separately backed up Sent items exist only on the device that sent them Configured to leave copies on the server, it quietly fills your quota instead
IF YOU ARE ON POP3 NOW
Switching to IMAP is straightforward, but mail already downloaded stays on that device. Set up IMAP alongside, then copy the old mail into the IMAP folders so it is on the server too.
