I am having a peculiar problem. I am using the plugin along with the widget in wordpress 3.0.1. Everything works fine and the mails are delivering. But when an invite is send to a mail with a period as allowed by gmail it sends the mail to the email address including portion after the period. For example I sent an invite to lalit.kishore@gmail.com but when I checked the mail delivery logs the mail was sent to kishore@gmail.com and the result was that the mail was not delivered. This was not the only instance and the same behavior was shown in mails having similar ids. I am sure there must be some solution to it.
In continuation with the above, I upgraded one of the users to administrator and tested sending invites. No mails were sent or delivered to the user. However, mails sent from admin were delivered. This is strange but it is happening.