On April 1st 2004 google made an announcement, which is still live Google Gets the Message, Launches Gmail.
Many people thought it was a April Fools joke, including me, as per this blog post Google Mail : gmail and Update on Gmail, from my one year old blog hosted on blogspot.
The main reasons that it was a potential april fools joke was that 1 gigabyte was huge when hosted web mail usually had a limit of 15 megabytes. The other reason was that no one should do product announcement on April 1st!
I had been using a thunderbird mail client previously, but had lost all my emails at one point due to a corrupted file (and no backups). My bad.
I was able to get a gmail email address very soon on April 4th after applying on April 2nd, I think because of having a blogspot blog (Google acquired them in 2003).
The other thing that made gmail so revolutionary was it was also one of the first consumer facing web 2.0 web applications heavily using AJAX (Asynchronous JavaScript And XML), rather than big page reloads for everything. (The other major AXAJ site was the image hosting site Flickr created by Stewart Butterfield and Caterina Fake).
Given that I’ve got 30 GB of email (but only ~300 unread emails), it might still be a April Fools prank. 🙁