What email header difference will my contacts see if I use Benchmark Email Authentication?
Benchmark Email includes your Sender ID if you’ve enabled the Email Authentication feature. This information is part of your email’s header, and if you use Outlook, Hotmail or MSN, your recipients will see the following headers:
Email Clients displaying only From Name (friendly name)

These includes Outlook Express, AOL, Comcast, MacMail
Email Clients displaying From Name (friendly name) and From Email
If Email Authentication is set off

If Email Authentication is enabled

These includes Microsoft Outlook, Hotmail, Entourage, Thunderbird