Disable SMTP Client Authentication – Powershell Exchange Online

How to disable SMTP Client Authentication in Powershell Exchange Online. This resolves the issues after enabling MFA with scan to mail.

  1. Open Windows PowerShell and run the following command
  2. Set-ExecutionPolicy RemoteSigned
  3. $UserCredential = Get-Credential
  4. Without MFA: Connect-ExchangeOnline -Credential $UserCredential -ShowProgress $true

With MFA:          Connect-ExchangeOnline -UserPrincipalName <UPN> -ShowProgress $true

  1. Connect-ExchangeOnline -UserPrincipalName <UPN> -ShowProgress $true
  2. Set-casmailbox user@domain.com -SmtpClientAuthenticationDisabled $false
  3. Check status with: Get-casmailbox user@domain.com | fl SmtpClientAuthenticationDisabled
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