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'Mailbox does not exist' Error When Configuring Office 365 in Web Help Desk

This article discusses how to resolve 'Mailbox does not exist' error when configuring office 365 in Incoming Mail Account using OAuth Authentication Mode in Web Help Desk

First published date

7/6/2021 5:53 PM

Last published date

2/8/2025 7:32 AM

Overview

Mailbox does not exist
Error shown above normally occurs even when you clicked Save after successfully authorized Open Authentication (OAuth)
 

Product section

Web Help Desk

Cause

Incoming Mail Account was authorized using a different account

Resolution

  1. Check if the account used for authorizing OAuth is the incoming mail account
     
  2. Incoming Mail Account should be used on authorizing OAuth
 
  1.  Make sure that Incoming Mail Account is User Type and not Shared Type.
  • Go to Exchange Admin Center
  • Select Recipients > Shared
  • Select the shared mailbox. Under Convert to Regular Mailbox, select Convert.
     
  1. Incoming Mail Account should have at least Application developer access
  • Go to Exchange Admin Center
  • Select Recipients > Mailboxes
  • Select the incoming mail account > Manage Admin Roles
  • Select Application developer under Admin center access
  • Save changes
     
  1. Go back to Web Help Desk > Incoming Mail Account
     
  2. Authorize > Save