Using classic Outlook for Windows in business environments
For synchronized email across several PCs, IMAP or an Exchange account is the better method than POP3.
- POP3 is designed mainly to download mail to one device. By default, downloaded messages are removed from the server, and POP3 does not synchronize folders, sent items, or read/unread state across devices.
- IMAP keeps messages on the server and synchronizes mailbox changes across multiple devices. Inbox, Deleted Items, and Sent Items can stay consistent between PCs and mobile devices.
- Exchange accounts also keep mail on the server and synchronize email, contacts, and calendar across devices.
If POP3 must remain in use, Outlook can be configured on each PC to reduce the problem:
- In Outlook, go to File > Account Settings > Account Settings.
- Select the POP3 account, then select Change.
- Select More Settings.
- On the Advanced tab, under Delivery, select Leave a copy of messages on the server.
That allows multiple PCs to download the same messages, but it still does not provide full synchronization of folders, sent mail, or message status.
For a setup that truly shares and synchronizes mailboxes across desktop, laptop, and iPad, moving the account from POP3 to IMAP is the practical approach. If the mailbox is hosted on Exchange or Microsoft 365, using the Exchange account type is preferable because it also synchronizes contacts and calendar.