Enable IMAP Setting

Perform the below steps to enable IMAP for your Microsoft Office 365 account:

1. Login to Office Admin Portal using http://portal.office.com.
2. From the Microsoft 365 admin center dashboard, navigate to Admin → Exchange.
3. Navigate to Recipients → Mailboxes.
4. Select the user for which you want to enable or disable POP3 or IMAP, and then click Edit icon.
5. In the User Mailbox dialog box, in the console tree, click Mailbox Features.
6. Under Email Connectivity, Enable or Disable POP3 or IMAP.
7. Click Save.