How to send Emails from PowerShell

Overview

There are several reasons why you may want to programmatically send emails with Windows PowerShell.  For example, you may want to automatically email users when their Active Directory passwords are about to expire, or when their AD account locks out.

In order to send emails directly from your either personal or company gmail account, we are going to need to allow access first. This means we need to allow “less secure apps” to authenticate.

A less secure app is basically anything that simply uses a username and password rather than something that uses OAuth tokens. In the security world, this is a very bad practice… but for the simplicity of this tutorial, I am going to do it anyway.

Enable access from "Less Secure Apps"

I went to my GSuite admin panel and allowed users to manager their less secure apps: https://admin.google.com/u/1/ac/security/lsa?hl=en

Google Admin Security Settings

Next I logged into the target account I wanted to send the emails from and enabled “Allow less secure apps”:  https://myaccount.google.com/lesssecureapps

Enable Less Secure Apps

Configure Your Credentials

Before we get started coding, I am going to configure the credentials I will be using to access my gmail account. I never like to store my passwords or credentials inside of my scripts so I am storing them inside of a text file on the C drive called "credentials.txt":

Credentials

Inside the text file I have the first line as the email I plan to send emails from and the second line is the password to the account... Of course this is just example data and not my real info:

Credentials2

We can access the contents of this file with the code below:

$username   = (Get-Content -Path 'C:\credentials.txt')[0]
$password   = (Get-Content -Path 'C:\credentials.txt')[1]

Of course if you'd rather just store your passwords in the script you can do so by modifying lines 7 and 8 in the script below to something like this:

$username   = "[email protected]"
$password   = "[email protected]$$w0rd"

Sending emails with PowerShell!

Now we can send emails programmatically from windows PowerShell. Below is the snippet of code I used to send emails:

function Send-Email() {
    param(
        [Parameter(mandatory=$true)][string]$To,
        [Parameter(mandatory=$true)][string]$Subject,
        [Parameter(mandatory=$true)][string]$Body
    )
    $username   = (Get-Content -Path 'C:\credentials.txt')[0]
    $password   = (Get-Content -Path 'C:\credentials.txt')[1]
    $secstr     = New-Object -TypeName System.Security.SecureString
    $password.ToCharArray() | ForEach-Object {$secstr.AppendChar($_)}

    $hash = @{
        from       = $username
        to         = $To
        subject    = $Subject
        smtpserver = "smtp.gmail.com"
        body       = $Body
        credential = New-Object -typename System.Management.Automation.PSCredential -argumentlist $username, $secstr
        usessl     = $true
        verbose    = $true
    }

    Send-MailMessage @hash
}

To send an email with this function you can run the command below:

Send-Email -To "[email protected]" -Subject "This is a test" -Body "This email was sent via PowerShell."
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