Registration of new user using Temporary mail should not be allowed

[yashwaghmare123]

The current authentication system allows users to register and log in using temporary/disposable email addresses. This presents a security and abuse concern, as malicious users can exploit this loophole to create multiple fake accounts, bypass rate limiting, or avoid accountability.

[p474nj4y]

I tested this and was able to register using a disposable email address. The account could star repositories and follow users. For comparison, I performed the same test on GitHub, where the stars and follows from newly created disposable-email accounts were later removed by GitHub's anti-abuse system. If similar protections are not in place here, this could allow fake engagement, spam, or reputation manipulation through multiple disposable accounts.