(PowerShell) POP3 Auto-Refresh Office365 Access Token

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Demonstrates how to automatically recover from an expired OAuth2 access token when OAuth2 authentication fails in the POP3 protocol. If the server responds with "-ERR Authentication failure: unknown user name or bad password.", then we refresh the access token and retry.

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

$mailman.MailHost = "outlook.office365.com"
$mailman.MailPort = 995
$mailman.PopSsl = $true

# Use your O365 email address here.
$mailman.PopUsername = "OFFICE365_EMAIL_ADDRESS"

# When using OAuth2 authentication, leave the password empty.
$mailman.PopPassword = ""

# Load our previously obtained OAuth2 access token.
$jsonToken = New-Object Chilkat.JsonObject
$success = $jsonToken.LoadFile("qa_data/tokens/office365.json")
if ($success -eq $false) {
    $($jsonToken.LastErrorText)
    exit
}

$mailman.OAuth2AccessToken = $jsonToken.StringOf("access_token")

# Make the TLS connection to the outlook.office365.com POP3 server.
$success = $mailman.Pop3Connect()
if ($success -ne $true) {
    $($mailman.LastErrorText)
    exit
}

# Authenticate using XOAUTH2
$success = $mailman.Pop3Authenticate()
if ($success -ne $true) {
    # If we're still connected to the mail server, then it means the server sent a non-success response,
    # Such as:  -ERR Authentication failure: unknown user name or bad password.
    if ($mailman.IsPop3Connected -eq $true) {

        # Refresh the OAuth2 access token, and if successful, save the new (refreshed) access token and try authenticating again.
        $oauth2 = New-Object Chilkat.OAuth2

        # Use your actual Directory (tenant) ID instead of "112d7ed6-71bf-4eba-a866-738364321bfc"
        $oauth2.TokenEndpoint = "https://login.microsoftonline.com/112d7ed6-71bf-4eba-a866-738364321bfc/oauth2/v2.0/token"

        # Replace these with your Azure App Registration's actual values.
        $oauth2.ClientId = "CLIENT_ID"
        $oauth2.ClientSecret = "CLIENT_SECRET"

        # Get the "refresh_token"
        $oauth2.RefreshToken = $jsonToken.StringOf("refresh_token")

        # Send the HTTP POST to refresh the access token..
        $success = $oauth2.RefreshAccessToken()
        if ($success -ne $true) {
            $($oauth2.LastErrorText)
            exit
        }

        $("New access token: " + $oauth2.AccessToken)
        $("New refresh token: " + $oauth2.RefreshToken)

        # Update the JSON with the new tokens.
        $jsonToken.UpdateString("access_token",$oauth2.AccessToken)
        $jsonToken.UpdateString("refresh_token",$oauth2.RefreshToken)

        # Save the new JSON access token response to a file.
        $sbJson = New-Object Chilkat.StringBuilder
        $jsonToken.EmitCompact = $false
        $jsonToken.EmitSb($sbJson)
        $sbJson.WriteFile("qa_data/tokens/office365.json","utf-8",$false)

        $("New Access Token = " + $oauth2.AccessToken)

        # Update the mailman with the new access token.
        $mailman.OAuth2AccessToken = $oauth2.AccessToken

        # Retry the authentication.
        $success = $mailman.Pop3Authenticate()
        if ($success -eq $false) {
            $($mailman.LastErrorText)
            exit
        }

    }
    else {
        $($mailman.LastErrorText)
        exit
    }

}

# Find out how many emails are on the server..
$numEmails = $mailman.CheckMail()
if ($numEmails -lt 0) {
    $($mailman.LastErrorText)
    exit
}

# Examine the POP3 session log:
$($mailman.Pop3SessionLog)

# The POP3 session log will look something like this:

# **** Connected to outlook.office365.com:995
# < +OK The Microsoft Exchange POP3 service is ready. [QwBIADIAUABSADEANgBDAEEAMAAwADEAMgAuAG4AYQBtAHAAcgBkADEANgAuAHAAcgBvAGQALgBvAHUAdABsAG8AbwBrAC4AYwBvAG0A]
# > AUTH XOAUTH2
# < + 
# > <base64 string in XOAUTH2 format>
# < -ERR Authentication failure: unknown user name or bad password.
# > AUTH XOAUTH2
# < + 
# > <base64 string in XOAUTH2 format>
# < +OK User successfully authenticated.
# > STAT
# < +OK 248 46637086

# End the POP3 session and close the connection to the GMail server.
$success = $mailman.Pop3EndSession()
if ($success -ne $true) {
    $($mailman.LastErrorText)
    exit
}

$("Finished.")