Version: 1.10.4 (using 4.1.4 (KDE 4.1.4), Kubuntu packages) Compiler: cc OS: Linux (x86_64) release 2.6.27-11-generic If you enter an .edu extension in the reply-to field of an identity, it refuses the input and will not allow you to save the option. Easily reproduced by following those simple steps.
It works for me in kmail 1.11.0 and 1.11.90 (kde 4.2.0 and kde 4.2.62). The only combination that does not allow to save it is "@.edu", that is invalid.
Fine let's close then. I can enter any .edu address in the reply-to field without getting any error.