diff --git a/FixDomainEmails/FixDomainEmails.ps1 b/FixDomainEmails/FixDomainEmails.ps1
new file mode 100644
index 0000000..06e0227
--- /dev/null
+++ b/FixDomainEmails/FixDomainEmails.ps1
@@ -0,0 +1,75 @@
+
+Import-Module ActiveDirectory
+
+$EmailDomain = "CHANGE ME.com"
+
+$UPNDomain = "CHANGE ME.com"
+
+$SearchBase = ""
+
+$FixProxyAddresses = $false
+$FixUPN = $false
+$DryRun = $false
+
+Write-Host "Loading users..." -ForegroundColor Cyan
+
+$Query = @{
+    LDAPFilter  = "(&(objectClass=user)(objectCategory=person))"
+    Properties  = "mail","proxyAddresses","userPrincipalName","sAMAccountName"
+}
+if ($SearchBase -ne "") { $Query.SearchBase = $SearchBase }
+
+$Users = Get-ADUser @Query
+
+Write-Host ("Users found: {0}" -f $Users.Count) -ForegroundColor Yellow
+
+foreach ($u in $Users) {
+
+    $desiredMail = "$($u.sAMAccountName)@$EmailDomain"
+    $desiredUPN  = "$($u.sAMAccountName)@$UPNDomain"
+
+    $changes = @()
+
+    if ($u.mail -ne $desiredMail) {
+        $changes += "mail → $desiredMail"
+        if (-not $DryRun) {
+            Set-ADUser $u -EmailAddress $desiredMail
+        }
+    }
+
+    if ($FixProxyAddresses) {
+        $newPrimary = "SMTP:$desiredMail"
+        $existing   = @()
+
+        if ($u.proxyAddresses) { $existing = @($u.proxyAddresses) }
+
+        $aliases = $existing | Where-Object { $_ -notlike "SMTP:*" }
+
+        $aliases = $aliases | Select-Object -Unique
+
+        $newProxy = @($newPrimary) + $aliases
+
+        if (-not $existing -or ($existing -join "|") -ne ($newProxy -join "|")) {
+            $changes += "proxyAddresses updated"
+            if (-not $DryRun) {
+                Set-ADUser $u -Replace @{ proxyAddresses = $newProxy }
+            }
+        }
+    }
+
+    if ($FixUPN -and $u.userPrincipalName -ne $desiredUPN) {
+        $changes += "UPN → $desiredUPN"
+        if (-not $DryRun) {
+            Set-ADUser $u -UserPrincipalName $desiredUPN
+        }
+    }
+
+    if ($changes.Count -gt 0) {
+        Write-Host "$($u.sAMAccountName): $($changes -join ', ')" -ForegroundColor Green
+    } else {
+        Write-Host "$($u.sAMAccountName): no changes needed" -ForegroundColor DarkGray
+    }
+}
+
+Write-Host "Done." -ForegroundColor Cyan
+