New Outlook IMAP Error: "Changing the ImapRemoteServerInfo is not allowed" After Email Hosting Migration

Problem Description

I am experiencing a persistent account setup failure with New Outlook for Windows following my organization's migration from its previous email hosting provider to Cloudvantage.

Our company email address remained unchanged; only the email hosting server changed.

Previous IMAP server: mail.omnicomsolutions.com.ng

New IMAP server: mail.cvgmail.com.ng

Since the migration, I have been unable to add my company email account to New Outlook. However, the same email account works perfectly in Outlook Classic using the new server configuration.

Error Message

When attempting to configure the account manually through Advanced Setup (IMAP), New Outlook displays:

"Something went wrong with this account setup. Try again or use a different account."

I investigated the issue using New Outlook Developer Tools (olk.exe --devtools) and inspected the failed network request.

The backend returned the following response:

{
  "idpStatusCode": "BadRequest",
  "error": "BadRequest",
  "errorDescription": "Changing the ImapRemoteServerInfo is not allowed. Attempted to changed it from 'mail.omnicomsolutions.com.ng' to 'mail.cvgmail.com.ng'",
  "innerError": null
}

Troubleshooting Already Completed

Verified that the email credentials are correct.

Confirmed the new Cloudvantage IMAP/SMTP server settings.

Attempted manual account configuration through Advanced Setup.

Disabled recommended automatic settings and entered the server details manually.

Confirmed that the account works in Outlook Classic.

Confirmed that no other devices or email applications are still using the previous server.

Captured the exact backend error using Developer Tools.

Assistance Required

The error appears to indicate that Microsoft's cloud-side account configuration still retains the previous IMAP server association and is rejecting the new server information.

I would appreciate assistance with the following:

Is there a supported way to clear or reset the existing ImapRemoteServerInfo association?

Can Microsoft reset or re-provision the affected IMAP account on its cloud infrastructure?

Does this require escalation to the New Outlook engineering team?

Is there a workaround that would allow me to add the account without losing existing mailbox data or affecting Outlook Classic?

I would particularly appreciate input from Microsoft Outlook engineers, moderators or MVPs who have encountered this specific error following an IMAP hosting migration.

Thank you.