Powershell script sends e-mail in ISE but not from powershell command line

I have created a script that generates a report of all users who do not have photos in Active Directory. The script runs and sends an e-mail to a distribution list. It runs fine in ISE, but I cannot run it from command line or as a scheduled task. Any suggestions what I am doing wrong?

#Starts Powershell Snap-In
############################################################################

Start-Transcript -path c:\Scripts\StaffWithoutPhotos.txt
add-pssnapin Microsoft.Exchange.Management.PowerShell.E2010 -erroraction silentlyContinue

#---------------------------------------------------------------------------


$mailboxes = $null

$mailboxes = @(Get-Mailbox -OrganizationalUnit "Staff User Accounts" -ResultSize Unlimited | Where {$_.HasPicture -eq $False})

Write-Host $mailboxes

$report = @()

foreach ($mailbox in $mailboxes)
{
$mbObj = New-Object PSObject
    $mbObj | Add-Member -MemberType NoteProperty -Name "Display Name" -Value $mailbox.DisplayName
    $report += $mbObj
}

Write-Host "Diagnostic Output"
Write-Host "Before Mailbox value check"
Write-Host $report
Write-Host "After Mailbox Value check"

if ($mailboxes -ne $null)
{
    Write-Host $report

    #Send the report generated to the e-mail list specified above
    ############################################################################

    $style = "<style>BODY{font-family: Arial; font-size: 10pt;}"
    $style = $style + "TABLE{border: 1px solid black; border-collapse: collapse;}"
    $style = $style + "TH{border: 1px solid black; background: #dddddd; padding: 5px; }"
    $style = $style + "TD{border: 1px solid black; padding: 5px; }"
    $style = $style + "</style>"

    #Start-Sleep -Seconds 5
    $smtpserver = "MAIL.contoso.com"

    $msg = new-object Net.Mail.MailMessage
    $smtp = new-object Net.Mail.SmtpClient($smtpServer)
    $msg.From = "exchangereports@contoso.com"
    $msg.To.Add("DL.StaffPhotos@contoso.com")
    #$msg.To.Add("jtest@contoso.com") #Used for testing
    $msg.Subject = "Staff without Photos report"
    $msg.Body = "This report contains the list of users who do not currently have photos."
    $msg.Body += "<p>"
    $msg.Body += "After photos are available for these users please submit a request to have their accounts updated or send an e-mail to <a href='mailto:ithelpdesk@contoso.com?Subject=Staff%20Photo%20Updates' target='_top'> ITHelpDesk@contoso.com</a> with <b>Staff Photo Updates</b> in the subject."
    $msg.Body += "<p>"
    $msg.Body += "This report runs on Fridays and will only send a message if we have Staff without Photos. For more information please contact your systems administrator."
    $msg.Body += "<p>"

    $msg.Body += $Report | ConvertTo-Html -Head $Style

    $msg.IsBodyHTML = $true
    $smtp.Send($msg)
}
Stop-Transcript