When I try to "Sign in with Microsoft" I am getting a "Cannot Authenticate" error message

Issue symptoms

I am trying to integrate my Office 365 email account with my Sell account. I follow the steps to integrate my email and when I select Sign in with Microsoft I get the error message Authentication: Cannot Authenticate.

Resolution steps

The error message Authentication: Cannot Authenticate indicates that the authorization of our OAUTH application on the Office 365 side was successful. However, when we tried to use the provided credentials to log in to the server to verify that the integration is successful, we ran into an SMTP AUTH error. See the following steps to resolve your issue:

Ensure the Username and Primary email address fields match in the Microsoft admin settings. If there is a mismatch, Microsoft will not allow for the email to integrate with Sell. If these fields match, continue to the next step.

The Office 365 email admin needs to enable SMTP AUTH on your Office 365 email account.
For more information, see the article: Use the Microsoft 365 admin center to enable or disable SMTP AUTH on specific mailboxes.

After enabling the email protocol, follow the steps to integrate your Office 365 email.

Important: Enabling SMTP alone will not resolve this error message. This email protocol is often disabled in Office 365 by default and an email admin needs to enable both IMAP and SMTP and SMTP AUTH for the mailbox, as these protocols are what Sell uses to synchronize and send emails in your account.

For more information, see the article: Troubleshooting email integration errors.