[jocoda]

tangential

... without marketing (e.g. gmail

I would hard disagree that there was no marketing.

gmail had one of the first really successful guerilla marketing campaigns imo. Google made the initial phase by "invite only". By making it exclusive, a whole ecosystem developed around getting invites so that you could have that @gmail.com account. By the time of the official launch they had captured what could losely be described as the influencers of the time.

Invite only has been tried a few times since then, but never to my knowledge has it been done as well.

[bigstrat2003]

I wouldn't say that word of mouth from satisfied users counts as marketing. Google didn't need to drum up interest, people did that by themselves. It was mind-blowing at the time to get a whole GB of storage space for email. People would've been banging down their doors with or without an invite-only system.