Outlook Wont Let Me Use Multiple Microsoft 365 Accounts

Outlook
1

Hi,

We need to use multiple M365 accounts in Outlook, but we're running into an issue.

When we try to add an account, we get an error and can't proceed.

Occasionally, signing out of both accounts and signing back in resolves the problem.

We've even set up a new AVD session host, but that didn't help.

Any help with this issue would be greatly appreciated.

2

Hi there,

I totally understand your frustration about not being able to use multiple Microsoft 365 accounts in Outlook. This can be really aggravating, especially when you need to manage different accounts for work or personal reasons.

Background and Possible Causes

Multiple Microsoft 365 accounts linked to one Outlook profile can cause unexpected behavior. Sometimes, Outlook gets confused about which account should be set as the “main” account for certain actions, leading to issues like yours.

Additionally, adding multiple Exchange accounts to the same profile can cause Outlook to use different permissions sets simultaneously, which isn’t a supported functionality. This can lead to confusion about which account is active and authorized.

Steps to Resolve the Issue

To resolve your problem, follow these steps:

  1. Disable Auto-Mapping for Shared Exchange Mailboxes: This can help prevent the overlapping permissions issues. The administrator should use the Exchange Management Shell to disable Auto-Mapping for the shared mailboxes.

  2. Remove Duplicate Accounts: Ensure that you haven’t added the same account multiple times. Go to Account Settings, select the duplicated account, and remove it to prevent any conflicts.

  3. Use the Correct Outlook Configuration:

    • Remove Unnecessary Accounts: Go to File > Info > Account Settings, and remove any unnecessary accounts linked to the same profile.
    • Add Additional Mailboxes: Instead of adding a second account, add the additional mailbox as a separate mailbox under your primary account. This helps maintain separate permissions for each mailbox.

  4. Check Account Licenses: Verify that all accounts have the necessary licenses. If some accounts lack proper licenses, they might not be fully supported in Outlook.

  5. Sign Out and Sign In: Occasionally, logging out of both accounts and signing back in can resolve the problem. This resets the account associations and permissions.

  6. New Outlook Setup: If you’ve recently switched to the new Outlook for Windows, it might be prompting you to log in for all existing accounts. Ensure that you have the correct licenses and that the accounts are supported in the new Outlook.

Conclusion

Adding multiple Microsoft 365 accounts to Outlook can be a bit tricky, but following these steps should help you manage your accounts smoothly. Keep an eye on any license limitations and permissions issues that might arise. Good luck, and let me know if you need further assistance