When I went through the process two years ago, every school instructed me to log in through the portal to get my decision.

Sometimes it can take much longer than 4-6 weeks. Two schools left me in limbo for MONTHS. They didn't have wait lists, so as they got responses from offers of admission, they would continue down these informal wait lists they compiled, until they filled the class. It was torturous.

Depends on the school. Ask them.

So I was just reading the thread about private schools and that they usually notify families by email for acceptance and regular mail for non acceptance (for SJC at least). Does anyone here know how graduate school acceptances are handled?
DS is applying to grad school and still has four more applications to complete. He has heard back from one school via email (requesting he log on to school portal) and that was an acceptance. Another school that he applied to at the same time was supposed to let him know in 4-6 weeks which would be about now. Do universities follow similar protocols with email for acceptance and snail mail for rejection? Just curious!