Im not a lawyer so there may be subtle details I don't understand, but broadly in England and Wales, you can be sued within either 6 years or 12 years from the date of a breach of contract depending on type of contract, in Scotland 15 years. I don't know about the US or rest of EU, but think carefully about deleting all your old emails. You might have something in there which would be very useful to defend yourself if this ever happened. You would regret this if you had built the next Facebook and some old acquaintance decided to stake a claim based on some gmail conversation from 10 years ago. Better to archive to a redundant backup system I would say.