Google co-founders Larry Page and Sergey Brin loved pulling pranks, so much so they began rolling outlandish ideas every April Fools’ Day not long after starting their company more than a quarter century ago. One year, Google posted a job opening for a Copernicus research center on the moon. Another year, the company said it planned to roll out a “scratch and sniff” feature on its search engine.

The jokes were so consistently over-the-top that people learned to laugh them off as another example of Google mischief. And that’s why Page and Brin decided to unveil something no one would believe was possible 20 years ago on April Fools’ Day.

It was Gmail, a free service boasting 1 gigabyte of storage per account, an amount that sounds almost pedestrian in an age of one-terabyte iPhones. But it sounded like a preposterous amount of email capacity back then, enough to store about 13,500 emails before running out of space compared to just 30 to 60 emails in the then-leading webmail services run by Yahoo and Microsoft. That translated into 250 to 500 times more email storage space.