It's Gmail's 20th birthday. Read the 'Heck, Yeah' memo announcing its launch.

• Gmail launched 20 years ago with 1 GB of free storage, email search abilities, and an enthusiastic "Heck, yeah" from Google's founders.
• Many people at the time thought it was an April Fools' Day prank because the date was April 1, 2004.
• Read Google's memo from that day announcing Gmail's debut.

Gmail turned 20 on Monday if you can believe it.

Some people all those years ago didn't believe it, actually, because the email provider debuted on April 1, 2004, leading some to think it was an April Fools' Day prank.

Three years before Steve Jobs unveiled the first iPhone, Gmail launched with 1 GB of free storage, which seems miniscule to us now but was more than 100 times as much as its competitors boasted at the time. Today, Google accounts come with 15 GB for free, spread across Gmail, Google Drive, and Google Photos.

It also came with features like the ability to search your inbox for a certain email, and the grouping of emails with their replies.

For better or for worse, Gmail is here to stay. Its market share as an email service is estimated to be second only to Microsoft Outlook, which predates it by nearly a decade.

Take a look at how Gmail came to be with the original memo announcing its launch:

Google Gets the Message, Launches Gmail

User Complaint About Existing Services Leads Google to Create Search-Based Webmail

Search is Number Two Online Activity – Email is Number One; "Heck, Yeah," Say Google Founders

MOUNTAIN VIEW, Calif. – April 1, 2004 UTC – Amidst rampant media speculation, Google Inc. today announced it is testing a preview release of Gmail – a free search-based webmail service with a storage capacity of up to eight billion bits of information, the equivalent of 500,000 pages of email. Per user.

The inspiration for Gmail came from a Google user complaining about the poor quality of existing email services, recalled Larry Page, Google co-founder and president, Products. "She kvetched about spending all her time filing messages or trying to find them," Page said. "And when she's not doing that, she has to delete email like crazy to stay under the obligatory four megabyte limit. So she asked, 'Can't you people fix this?'"

The idea that there could be a better way to handle email caught the attention of a Google engineer who thought it might be a good "20 percent time" project. (Google requires engineers to spend a day a week on projects that interest them, unrelated to their day jobs). Millions of M&Ms later, Gmail was born.

"If a Google user has a problem with email, well, so do we," said Google co-founder and president of technology, Sergey Brin. "And while developing Gmail was a bit more complicated than we anticipated, we're pleased to be able to offer it to the user who asked for it."

Added Page, "Gmail solves all of my communication needs. It's fast and easy and has all the storage I need. And I can use it from anywhere. I love it!"

Today, a handful of users will begin testing the preview version of Gmail. Unlike other free webmail services, Gmail is built on the idea that users should never have to file or delete a message, or struggle to find an email they've sent or received. Key features of Gmail include:

• Search: Built on Google search technology, Gmail enables people to quickly search every email they've ever sent or received. Using keywords or advanced search features, Gmail users can find what they need, when they need it.

• Storage: Google believes people should be able to hold onto their mail forever. That's why Gmail comes with 1,000 megabytes (1 gigabyte) of free storage – more than 100 times what most other free webmail services offer.

• Speed: Gmail makes using email faster and more efficient by eliminating the need to file messages into folders, and by automatically organizing individual emails into meaningful "conversations" that show messages in the context of all the replies sent in response to them. And it turns annoying spam e-mail messages into the equivalent of canned meat.

According to Page and Brin, Google will make the preview test version of Gmail available to a small number of email aficionados. With luck, Gmail will prove popular to them – and to the original user who sparked the idea.

Those interested in learning more about Gmail can visit gmail.google.com.