I've been testing the new e-mail feature from the moment it was released, and I ran into a lot of trouble. Most of this trouble was caused by firewalls and virus scanners that filter the e-mail traffic in the network. One rather persistent error was caused by the scanner on my PC. If anyone of you gets an "error 10053", have a look at your virus scanner. If scripts are scanned (which is a sensible thing to do) then Cardbox will be seen as a mass mailing worm and the connection will be blocked. You'll have to exclude Cardbox or switch off script scanning entirely, which of course is a dangerous thing to do.
All anti-virus products should provide the ability to permit specific programs to send email. Finding which options to set can be difficult, since the user interface of these products is often badly designed or deliberately obscure. I suggest that anyone who has had to adjust anti-virus settings should report, as a reply to this message, what settings needed to be adjusted.
In McAfee: Start the VirusScan Console from the Start menu, right-click "Access Protection" and choose "Properties" from the menu. You're now in the tab "Port Blocking". The first option is "Prevent mass mailing worms from sending mail". Select this option and click "Edit". Add "Cardbox3" to the list of processes that are allowed to send e-mail.