Check E-mail Addresses From File

Posted on Aug 10, 2017 in IT Nerd Blog by stoff 0 Comments

SCENARIO
You’re handed a list of e-mail address for mass mailing from HR and they need to verify that all e-mail addresses are valid and won’t bounce “like last time”.

PROBLEM
There are a few problems with this. One is the fact that not all e-mail addresses are the primary e-mail address and won’t show up in a normal search.

SOLUTION
I put this little script together that will first connect to your MS Online tenant, then read all MSOL users into an array, import the CSV file containing the employees, go through each row and check that the e-mail address from the file in the column “employeeemailaddress” exists as a proxy address on at least one user. If not it writes out the e-mail to a log in c:\temp. Nothing too advanced, just a few things put together to achieve a very, VERY tedious task when you get a list of 10.000 e-mail addresses!

This can also be modified to check if any other attribute exists or not on users if you want to, it was just for this scenario that I had to check e-mail addresses! It can also be modified to read out the local AD and not the Azure AD, ofcourse.

Please comment out the first two lines if you run this more than once in a Powershell window since the list of users is already in the variable and reading out all MSOLUsers can take a very long time!

connect-msolservice 
$allusers = Get-MsolUser -All

#Prepping the logg
$DateStamp = Get-Date -Format "yyyy-MM-dd-HH-mm"
$LogFile = ("C:\temp\invalid_emailaddresses-" + $DateStamp + ".log")
# Defining the log function
Function LogWrite
{
Param ([string]$logstring)
Add-content $Logfile -value $logstring
}

$csv = import-csv C:\temp\emailaddresses.csv
foreach($csvobject in $csv)
{
    $emailuser = ""
    $emailaddress = $csvobject.employeeemailaddress
    Write-Host -ForegroundColor Yellow "Looking up user with e-mail $emailaddress"
    $emailuser = $allusers | where {$_.proxyaddresses -like "*$emailaddress*"} | select DisplayName
    if(!$emailuser.displayname)
    {
        LogWrite ("Could not find user with e-mail address $emailaddress")
        write-host -ForegroundColor Red "Could not find user with e-mail address $emailaddress"
    }
    else
    {
        write-host -ForegroundColor Green "User found, e-mail address is good"
    }
}

Tags: Exchange Online, Office 365, Powershell