What email header difference will my contacts see if I use Benchmark Email Authentication?
Benchmark Email includes the Sender ID if you have enabled the Email Authentication.
This information is part of the email header. Outlook, Hotmail, and MSN webmail
clients would display these headers to the recipients.
Email Clients displaying only From Name (friendly name)

These includes Outlook Exprees, 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