Are you saying that there are sites out there which don't accept [email protected] a valid email address? If so, that's beyond broken...
Sorry, could you repeat that? [email protected] certainly matches \.edu$.
Unless you're worried about the false-positive for a non-student with a different subdomain?
Only one university in Germany has a .edu, and their students obviously manage to get far more benefits than those of us with an @informatik.uni-kiel.de email.
In Brazil, universities can use .edu.br, but we have few universities providing email addresses to students and also, the majority of grad schools in Brazil are not universities but a small college called 'University Center'
I'll note that I don't use this method as it seems too high maintenance and the effectiveness is unclear.
Hasn't been a problem for me.
I haven't found this to be true, or at least Google's spam filters have gotten sufficiently good to prevent it.
I have a catch-all address @morgante.net and rarely ever see spam—maybe once a week.
An intermediate step that may work if you don't expect people to target you individually: have one or more required substrings for the email local part, and catch all mail to addresses containing that substring.