What is the 'This email used to send emails:' field for?

Awesome module. Works like a charm :)

What is the This email used to send emails: field for? This field can be found under admin/settings/ecard Whatever email address I type in there're are no change in the emails send. Find below screenshot to clarify (ecard-settings.png).

I searched the issues queue, README.txt and INSTALL.txt files but found nothing.

I changed the value to noreply@mydomainnamehere.com. And was expecting that when a ecard is send the email send to the recipient would read email from: noreply@mydomainnamehere.com Instead it reads email from: mynamehere@mydomainnamehere.com. It uses the value under admin/settings/site-information Find other below screenshot to clarify (site-information-settings.png).

Using Ubuntu Server 8.04 LTS for site hosting with Postfix version 2.5.1 for mail server.