PowerShell script to export SSL Certificate delivery emails to .crt files

Get-SslCertFromThawteApprovalEmail.ps1

# Automates Outlook
# - searches the Inbox for Thawte 
#    'your SSL certificate has been approved' messages
#  - extracts the certificate to disk with a useful filename
#  - deletes the emails

$VerbosePreference = 'continue'

$OutputFolder = '\\server\share\SSL Cert Deliveries\'

Write-Verbose -Message "Writing to output folder: '$OutputFolder'"

$sslCertSubjects = @(
    'Your Thawte SSL123 Certificate Is Approved'
    'Your SSL Web Server Certificate Is Approved'
    'Your SSL Web Server Wildcard Certificate Is Approved'
    'Your SSL Web Server with EV Is Approved'
)

$outlook = New-Object -ComObject Outlook.Application

$namespace = $outlook.GetNameSpace("MAPI")
$inbox = $namespace.GetDefaultFolder(6) #6 is Inbox

$inbox.Items | Where-Object {

    $sslCertSubjects -contains $_.Subject
   
} | ForEach-Object {

    Write-Verbose -Message "Checking {$($_.Subject)} Email sent on $($_.SentOn)"

    if ($_.SenderEmailAddress.endsWith('@thawte.com') -and $_.Body -match '(?ms)Order number: (?<OrderNumber>[^\r\n]+).*common name: (?<CN>[^\r\n]+).*(?<Cert>-----BEGIN CERTIFICATE-----.*-----END CERTIFICATE-----)')
    {

        Write-Verbose -Message "Processing Email sent on $($_.SentOn)"

        # read the certificate's "valid from, until" properties
        $Cert = New-Object System.Security.Cryptography.X509Certificates.X509Certificate
        $Cert.Import([System.Text.Encoding]::ASCII.GetBytes($Matches['Cert']))
        $StartDate = [datetime]::ParseExact($Cert.GetEffectiveDateString(),  'dd/MM/yyyy HH:mm:ss', [cultureinfo]::InvariantCulture)
        $EndDate   = [datetime]::ParseExact($Cert.GetExpirationDateString(), 'dd/MM/yyyy HH:mm:ss', [cultureinfo]::InvariantCulture)
        
        
        # Make a filename
        $FileBaseName = '{0} - {1} - {2} to {3}.crt' -f $Matches['OrderNumber'], $Matches['CN'].Trim(), $StartDate.Year, $EndDate.Year
        
        
        # make filename valid for wildcard certs *.example.com
        $FileBaseName = $FileBaseName.Replace('*', 'star')
        $FileFullName = Join-Path -Path $OutputFolder -ChildPath $FileBaseName
        
        
        Write-Verbose -Message " Certificate details / filename: $FileBaseName"

        
        if (-not (Test-Path -LiteralPath $FileFullName))
        {
            $null = New-Item -ItemType File -Path $FileFullName -Value $Matches['Cert']
        }
        else
        {
            Write-Verbose -Message " File exists already, not writing"
        }

        $_.Delete()
    }
    else
    {
        Write-Verbose -Message "Email wasn't from Thawte, or body didn't match the SSL cert regex"
    }

}