[Kazun]

Код:

Send-MailMessage ....... -Credential "" -Port 587 -UseSsl

или

Код:

$SMTP = New-Object Net.Mail.SmtpClient($SmtpServer, 587) 
$SMTP.EnableSsl = $true 
$SMTP.Credentials = New-Object System.Net.NetworkCredential("username", "password")
$SMTP.Send($SMTPMessage)