On the iPhone it works by opening Mail.app and there you can select the outgoing email address (i've got 4 configured) and i happened to chose the one which has

On the iPhone it works by opening Mail.app and there you can select the outgoing email address (i've got 4 configured) and i happened to chose the one which has my clearname as for it to be recognized by the people i've sent the invite to. (probably forgot to mention that i've used the Dropbox app on the iPhone to send out the invites)