No! NO NO NO. Not 5. He said 10. Nobody's doing 5. Who uses email for 5 minutes? 10's the key number here. 10 commandments! 10 doors! 10, man, that's the number. 10 chipmunks twirlin' on a branch eatin' lots of sunflowers on my uncle's ranch! Step into my office!

When the comment above this is what I thought of, but didn't post it, I thought it didn't 'add' to the conversation, but whatever, I don't know the source of this saying is but it reminds me of the hitchhiker in Something about Mary.

Hitchhiker: Step into my office. Ted: Why? Hitchhiker: 'Cause you're f*in' fired!

Yeah, that's where it's from.

You could test it with Google Adwords. Put up ads for "10 minute mail", "5 minute mail", "30 minute mail", and "42 minute mail", and see which one gets the most clicks.

I heard Tim Ferriss claim that this is how he picked the title for his book, "The Four-Hour Workweek".

On the other hand, you could also just pull 10 minutes out of the air and say "that sounds about right". Which it does.

Um... Or you could use Google Trends. http://google.com/trends/

Common Man that's just stupid, nobody will buy that!

umm, i think to improve the service you want to increase the expropriation time of the e-mail address. so "why stop as 10 minutes! Whats about 15 minute e-mail? ;)

There's a helpful "give me 10 more minutes" link on the site.