You may have to enable POP3 or disable POP3 for your Office 365 email account if you are connecting your email to an external app.
Follow these steps to disable or enable PO3 from Office 365 Admin Center. You should have admin access on the account.
Step 1. Sign in to your Office 365 Admin Center visiting admin.microsoft.com
Step 2. In the Admin dashboard, find Exchange link in the left side bar of the menu links and click it. This will take you to the Exchange admin center. This is where you can manage your email accounts and their settings.
Step 3: Select and expand Recipients and select Mailboxes.
![Exchange admin center]()
This will load all current mailboxes for your mail server.
Step 4: Select the user that needs POP3 or IMAP settings changed. This will load user details dialog box where you can change user settings.
Step 5: Find Email apps heading at the bottom of the dialog box. If you don’t see it, scroll down. Here you will see that you can change default settings for Outlook on the web, IMAP, POP3, MAPI and more.
![Office 365 email settings]()
Click on Manage email apps settings link.
Step 6: On the next dialog, you can enable or disable all these settings including POP3 and IMAP.
![Office 365 email apps settings]()
Step 7. Save changes when you are done.
Hope you were able to enable or disable POP3 settings of your Office 365 mail account.