I created a LiveCycle (v8.2.1) form with the email submit button. Works fine if the sender is using Outlook. If their using Thunderbird, it does not. I installed Thunderbird on my system (normally I use Outlook) and set Control Panel/Internet Options/Programs email to use Mozilla Thunderbird as the email program. When I click the Email button on my LiveCycle PDF form, I get a message telling me: Select an Email Client. The "Desktop Email Application" radio button is checked and that should be fine; the explanation for this button indicates that it should be checked "if you currently use an email application such as Microsoft Outlook Express, Microsoft Outlook, Eudora, or Mail.". I leave that checked, since I am using an email application and click OK. After 20-30 seconds, I get a message with the title bar: Microsoft Office Outlook "A program is trying to access e-mail address information stored in Outlook..." Allow|Deny|Help. I click Deny. After a minute or so, an Outlook "New" email window appears with the appropriate information from my LiveCycle PDF form. Right content, wrong email client. Since Thunderbird is my "default" email application, where is LiveCycle coming up with Outlook? What do my customers do who don't use Outlook?