(PowerShell) Verify Email Recipients

A way to possibly determine valid/invalid email addresses. I would recommend being very careful about doing this because your IP address may be flagged as a potential spammer by the mail server (because you are probing for valid/invalid email addresses). This Chilkat functionality existed for many years, before this kind of activity became a problem. The functionality remains only because it is useful for some to test with their own SMTP servers.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$mailman = New-Object Chilkat.MailMan

# SMTP connection settings...
$mailman.SmtpHost = "smtp.example.com"
$mailman.SmtpUsername = "MY_SMTP_USERNAME"
$mailman.SmtpPassword = "MY_SMTP_PASSWORD"
$mailman.SmtpSsl = $true
$mailman.SmtpPort = 465

# Create a new email object
$email = New-Object Chilkat.Email

$email.Subject = "This is a test"
$email.Body = "This is a test"
$email.From = "myemail@example.com"
$success = $email.AddTo("person1","person1@example.com")
$success = $email.AddTo("person2","person2@example.com")
$success = $email.AddTo("person3","person3@example.com")
# The SMTP server smtp.example.com won't know anything about an email address @somewhere_else.com
$success = $email.AddTo("person3","person4@somewhere_else.com")
# ...

# Verify recipients.
# **** See the warning about using this API method in the description above.
# (An SMTP server only knows valid email address for its own domain.  For example,
# smtp.example.com *may* only know if person1@example.com is valid or invalid, but does
# not know anything about the validity of email addresses having other domains.)
$badAddrs = New-Object Chilkat.StringArray
$success = $mailman.VerifyRecips($email,$badAddrs)
if ($success -ne $true) {
    $($mailman.LastErrorText)
    exit
}

$i = 0
while ($i -lt $badAddrs.Count) {
    $($badAddrs.GetString($i))
    $i = $i + 1
}

$("done.")