I don't know if publishers have a plan where they deposit it in author's bank accounts or not. If not, then check. You can't e-mail a check; there's no reputable bank that will cash a check printed by a printer. Standard mail or direct deposit is how the money is sent. THey might get a royalty statement by e-mail. But, as far as the actual money goes then its probably by check.
If the author has an agent then the publisher sends the check to the agent and the agent takes out their commission and sends the rest to the author.
It's stipulated within the author-publisher contract when they'll get paid. So the author might get a royalty statement and check 4 times a year, for example.
HTH. This is from in-depth research I've done on publishing because I'm an aspiring author. This information comes from the different literary agents and author blogs I've read.