Unable to Access an Account or Mailbox
Resolving duplicate user account conflicts in Office 365.
Last updated: 2025-01-15 Troubleshooting
Overview
Error Message
"Unable to access an account or mailbox."
Duplicate Account Conflict
👤
Active User
user@domain.com
⚡
👻
Deleted User
Same identity
→
❌
Conflict
Can't identify
Root Cause
Duplicate User Accounts
The issue typically stems from Office 365 being unable to identify the correct mailbox for connection. This commonly occurs when duplicate user accounts exist in the system — one active account and one in the deleted accounts list.
Why This Happens
- • A user was deleted and recreated with the same email
- • Soft-deleted user still exists in the deleted users list
- • Office 365 cannot determine which account to connect to
- • Migration fails due to identity ambiguity
Solution
Remove Duplicate from Deleted Users
1
Access Office 365 Portal
2
Navigate to Users
Navigate to the administration area and locate the user list
3
Access Deleted Users
Click on "Deleted users" section to view soft-deleted accounts
4
Remove Duplicate
Identify and permanently remove the duplicate account
After Removal
After removing the duplicate from deleted users, retry the migration.
The mailbox should now be accessible without conflicts.