Updating Active Directory users email with Powershell - powershell

Question

I need to change a lot of users "email" field on their active directory profile however I cant seem to find the answer Im looking for looking at other posts.
I`m quite new to powershell but I've landed this task to be done at work.
The email address format is in the style of "first name" and "lastname" seperated by a "." with the domain appended on the end naturally.
An example would be John.Doe#domain.com
How would I go about this with powershell with users in 6 different OUs but all under the same root OU?
Kind regards

Answer 1

It depends on how you have the data. If you already have the emails in say a csv with a column titled "OldEmail" and "NewEmail" you could do something like:
$csv = import-csv \\path\to\csv
foreach($user in $csv) {
get-aduser -filter {mail -eq $user.OldEmail} | Set-ADUser -EmailAddress $user.NewEmail
}

Answer 2

You could do something like below, but as always when changing stuff in Active Directory,
try it out on a bunch of testusers first
# enter the root OU DistinguishedName where the sub OU's are here
$rootOU = "OU=Users,DC=yourdomain,DC=com"
# Get a list of user objects that do not have an email address in 'firstname.lastname#yourdomain.com' format.
# you only have to ask for property EmailAddress (LDAP name is 'mail'), because these properties are returned by default:
# DistinguishedName, Enabled, GivenName, Name, ObjectClass, ObjectGUID, SamAccountName, SID, Surname, UserPrincipalName
Get-ADUser -Filter * -SearchBase $rootOU -SearchScope Subtree -Properties EmailAddress |
Where-Object { $_.EmailAddress -ne ('{0}.{1}#yourdomain.com' -f $_.GivenName, $_.Surname) } |
ForEach-Object {
$mail = '{0}.{1}#yourdomain.com' -f $_.GivenName, $_.Surname
Write-Host "Setting up email address $mail for user $($_.SamAccountName)"
$_ | Set-ADUser -EmailAddress $mail
}