1. Back up your mailboxes

Switching from a POP3 connection to IMAP can result in your existing email being deleted, so you should create a backup of your mailboxes to avoid this

Open Outlook and select File.  In the menu that appears, select Open & Export, then Import/Export.

In the Import and Export window, select Export to a file and click Next >.

In the next window, Export to a File, select Outlook Data File (.pst) and click Next >.

You can now select the mailbox to back up. Select your email address in the Export Outlook Data File window and ensure the box next to Include subfolders is checked. Click Next > to continue.

Use the Browse button to select a location on your computer for your backup. Click Finish to continue.

Enter a password and click OK, or Cancel to proceed without a password.

The backup will now be saved.

2. Delete your POP account

With the backup completed, you can now delete the POP account in Outlook. You should also delete the account on any other devices you use for email.

Select File from the top menu, then Info.

Click the arrow next to Account Settings and select the Account Settings… option which pops up.

In the Account Settings window, click on your email account then click Remove to delete it from Outlook.

You’ll be warned that your offline messages will be deleted. Click Yes to continue.

3. Set up your IMAP account on your computer

The final step is to create a new email account using IMAP server details. You can use the New… button in the Account Settings window to get started or alternatively, click File in the top menu, then Add Account.