User authentication is provided by methods of FML::Credential class.
For the user@domain address, we handle user part as case sensitively and domain as case insensitively. Is it better to prepare the option that handling of user part is insensitive? (Yes, I think so.)
author's homepage is www.fml.org/home/fukachan/.
Also, visit nuinui's world :) at www.nuinui.net.
For questions about FML, e-mail <fml-bugs@fml.org>.