how do i find out if iphone is not POP3

For deleting an email on the iPhone to also remove it from the PC, the account on both devices must use IMAP, Exchange, Microsoft 365, or Outlook.com synchronization—not POP3.

Check the account type on the PC

In classic Outlook for Windows:

1. Select File → Account Settings → Account Settings.
2. Find the email account and check its Type column.
3. You want to see IMAP, Microsoft Exchange, or a similar server-based account type—not POP/POP3.

If necessary, select the account and choose Change; the window also displays the account type. The Leave a copy of messages on the server setting appears only for POP3 accounts, which is another indication that the account uses POP3.^1^

This PC check is important: even if the iPhone deletes the server copy, Outlook may retain an already-downloaded local copy when the PC is configured for POP3.

Check the iPhone

The path depends on the app being used:

• Outlook for iOS: Accounts such as Microsoft 365, Outlook.com, Google, Yahoo, and iCloud are detected and configured automatically according to their account type.^2^
• Apple Mail: Open Settings → Apps → Mail → Mail Accounts, then select the email account. If it was added as Microsoft Exchange, it is server-synchronized. Microsoft’s current setup procedure uses Add Account → Microsoft Exchange for Microsoft 365, Exchange, and Outlook accounts.^3^

For a Gmail, Yahoo, iCloud, or internet-provider address, check the account details for IMAP or contact that email provider if iOS does not display the protocol clearly.

What the account types mean

• IMAP: Mail and changes are stored on the server and synchronized across devices. Deleting a message on the iPhone removes it from the synchronized mailbox and therefore from the PC.
• Exchange, Microsoft 365, or Outlook.com: These are also server-synchronized when added using the corresponding account option.
• POP3: Primarily downloads messages to one device and does not provide normal two-way synchronization. A message deleted on the iPhone might remain as a downloaded copy on the PC.^4^

Do not remove and re-add an account until any locally stored POP mail has been backed up. If the PC shows POP3, changing to IMAP or Exchange normally requires adding the account again using the email provider’s supported account type and server settings.

References

1. Leave a copy of the message on the server is missing in Outlook | Microsoft Support
2. Account setup with modern authentication in Exchange Online
3. Set up an Outlook account on the iOS Mail app
4. What is the difference between POP and IMAP? | Microsoft Support