just installed and tested this plugin in the latest WP ver 3.5.1 and it works like a charm..
However, there is 1 small issue:
When a new user register he receives an email with his MSL Secure Card, but this email is located in the SPAM folder instead of users inbox.
I have checked the spam server logs, and it seems that the real reason why this email is being considered as a spam is the MSL Secure Card name which plugin generates, for example: sdh237d28d7gwgba78213d.png
Can You please change the code, so the generated MSL Secure Card name is more familiar as for example: YourMSLCard.png
PS: this is not the issue on all email servers, but some of them consider this email as a spam...