Australian internet service providers (ISP) allow to send emails using their SMTP relays.

It’s pretty easy to send an e-mail from PowerShell:

send-mailmessage -from "Peter <This email address is being protected from spambots. You need JavaScript enabled to view it.>" -to "Oscar <This email address is being protected from spambots. You need JavaScript enabled to view it.>" -subject "Hello! How r u?" -smtp mail.bigpond.com -body "Buy one, get one free!!!"

You can also use server with authentication:

$EmailFrom = This email address is being protected from spambots. You need JavaScript enabled to view it.
$EmailTo = This email address is being protected from spambots. You need JavaScript enabled to view it.
$Subject = "Hello! How r u?"
$Body = "Buy one, get one free!!!"
$SMTPServer = “smtp.gmail.com”
$SMTPClient = New-Object Net.Mail.SmtpClient($SmtpServer, 587)
$SMTPClient.EnableSsl = $true
$SMTPClient.Credentials = New-Object System.Net.NetworkCredential(“usr”, “pass”);
$SMTPClient.Send($EmailFrom, $EmailTo, $Subject, $Body)

You will need to change the following:
$EmailFrom = Your GMail address.
$EmailTo = The recipient’s email address.
$Subject = What you want the subject of the mail to say.
$Body = What you want the main part of the mail to say.
usr = You will need to replace this with your GMail username.
pass = You will need to replace this with your GMail password.

Tips: Send HTML Formatted Emails using PowerShell.