Adding a Second Outlook Account from a Different Domain Using PowerShell

Question

An attempt was made to add or map a second Outlook account under the same profile through a PowerShell script, but it was unsuccessful despite the script reporting a successful status. Below is the PowerShell script used:

# Ensure Outlook is closed before making changes
Stop-Process -Name outlook -Force -ErrorAction SilentlyContinue
Start-Sleep -Seconds 3

# Ask for second email details
$SecondaryEmail = Read-Host "Enter the second email (e.g., ******@123xyz.onmicrosoft.com)"
$Password = Read-Host "Enter the password for $SecondaryEmail" -AsSecureString

# Convert password to plain text for use in the script (only during execution)
$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($Password)
$PlainPassword = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR)

# Define Outlook Profile Registry Path
$ProfilePath = "HKCU:\Software\Microsoft\Office\16.0\Outlook\Profiles\Outlook"

# Ensure the Outlook Profile exists
If (!(Test-Path $ProfilePath)) {
    Write-Host "Creating new Outlook profile..."
    New-Item -Path $ProfilePath -Force | Out-Null
}

# Generate unique registry key for the new account
$AccountKey = (New-Guid).Guid
$NewAccountPath = "$ProfilePath\9375CFF0413111d3B88A00104B2A6676\$AccountKey"

# Add the secondary email account with IMAP and SMTP settings
Write-Host "Adding $SecondaryEmail to Outlook Profile..."
New-Item -Path $NewAccountPath -Force | Out-Null
Set-ItemProperty -Path $NewAccountPath -Name "AccountName" -Value $SecondaryEmail -Force
Set-ItemProperty -Path $NewAccountPath -Name "Email" -Value $SecondaryEmail -Force

# IMAP Settings
Set-ItemProperty -Path $NewAccountPath -Name "IMAPServer" -Value "outlook.office365.com" -Force
Set-ItemProperty -Path $NewAccountPath -Name "IMAPPort" -Value 993 -Force
Set-ItemProperty -Path $NewAccountPath -Name "IMAPUseSSL" -Value 1 -Force

# SMTP Settings
Set-ItemProperty -Path $NewAccountPath -Name "SMTPServer" -Value "smtp.office365.com" -Force
Set-ItemProperty -Path $NewAccountPath -Name "SMTPPort" -Value 587 -Force
Set-ItemProperty -Path $NewAccountPath -Name "SMTPUseTLS" -Value 1 -Force

# Store Password (Not recommended for production; consider secure vaults)
Set-ItemProperty -Path $NewAccountPath -Name "Password" -Value $PlainPassword -Force

# Restart Outlook
Start-Process "outlook.exe"
Write-Host "Successfully added $SecondaryEmail to Outlook with IMAP/SMTP. Restart Outlook to verify."

Despite the "Successfully added" message, the new account does not appear in the account settings. What steps could be taken to troubleshoot this issue?