I have noticed that when users' email addresses include periods in the name (eg. john.smith@... as opposed to johnsmith@...) they are not recorded properly in the resulting admin notification email and the Form entry; all that is displayed is the text before the period, eg:
I am using the PayPal standard add-on and can verify that the full email is recorded by PayPal.
This has happened to a few users to it's safe to say that it's not an issue of the users mistyping their email addresses.
Any thoughts? I haven't found this exact issue elsewhere in the forums.