When did Gmail launch and how did it change email?

Gmail launched on April 1, 2004. Most people thought it was an April Fools joke because the offer sounded impossible: 1GB of free storage when Yahoo Mail and AOL were offering 2-4MB. You had to delete emails constantly just to stay under the limit. Gmail changed that overnight.

The launch changed email in three ways that still shape how mailboxes work today. First, search replaced folders. Gmail's interface assumed you'd never delete anything and just search when you needed it. Second, threaded conversations grouped replies together instead of showing every email separately. Third, and this matters most for senders: Gmail introduced aggressive spam filtering that analyzed content and sender behavior, not just keywords. That filtering approach became the industry standard. Every major mailbox provider now uses behavior-based reputation systems because Gmail proved it worked.

For email senders, Gmail's launch marked the moment when deliverability became complicated. Before Gmail, getting into the inbox mostly meant avoiding spam trigger words and keeping your IP off blocklists. After Gmail, you had to think about engagement (do people open your emails?), sender reputation (does your domain have a history?), and authentication (can mailboxes verify you're really you?). Gmail's filtering forced the entire industry to mature.

One detail people forget: Gmail was invite-only for the first three years. You couldn't just sign up. You needed an invitation from someone who already had an account. That scarcity made Gmail feel exclusive and drove massive demand. By the time it opened to the public in 2007, it had already reshaped expectations for what email should be.

And if you're curious how deliverability evolved after Gmail forced everyone to compete on filtering quality, check out how deliverability became its own discipline.