When Gmail launched with a goofy press release 20 years ago next week, many assumed it was a hoax. The service promised a gargantuan 1 gigabyte of storage, an excessive quantity in an era of 15-megabyte inboxes. It claimed to be completely free at a time when many inboxes were paid. And then there was the date: the service was announced on April Fools’ Day, portending some kind of prank.
But soon, invites to Gmail’s very real beta started going out — and they became a must-have for a…