If you are using any Microsoft email server, you will need to allow Method's IP address access, else you will get the following error even though both your email and password is correct:
535: 5.7.3 Authentication unsuccessful
1. Login to https://account.microsoft.com/account.
2. Select Security → Sign-in Activity.
3. Click the "This was me" button corresponding to Method's IP address.
Microsoft should now allow activity from Method.