Cannot Connect Office365 Account

[dejannenov]

I have checked existing reports and have not found a resolution

Description

Add Account → Office 365 → Browser Launches and Microsoft Office 365 Credentials Entered → Access Confirmed in Microsoft Permissions Window → Browser Says “You are all set” → MailSpring Account adding Pop-up Show Message ""Authentication Error - Check your username and password (SMTP)
In the Microsoft Administration for the company (https://entra.microsoft.com/) Mail spring appears as an activated app.

To Reproduce…

Steps to reproduce the behavior:

1. Add Account

2. Office 365

3. Login to Microsoft 365 Account & Grant MailSpring Permissions

4. In the MailSpring add account window see error: Authentication Error - Check your username and password. (SMTP)

Expected Behavior

Office365 Email Account Appears in the Mailspring UI

Screenshots

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Screenshots Added

Setup

• OS and Version: Windows 11 Pro Version 25H2 (OS Build 26200.8117)
  • Installation Method: Lenovo Laptop Windows 11 Pro Pre-installed and regularly updated
• Mailspring Version: 1.19.1 - 66f9e225 (Pro)

Additional Context

[dejannenov]

I was able to resolve my own problem.

Under the covers MailSpring uses generic/old-school IMAP/SMTP access to connect to a Microsoft Office365 account. Therefore the user’s account MUST have IMPA/SMTP permissions turned on by the administrator of the organization (which is problematic for corporate accounts).

Here is a screenshot of what needs to be turned on:
(Accessed at: https://admin.cloud.microsoft/)