I wrote and publish a book through leanpub about Ember.js: ember-cli-101. I started to sell it without finishing it and it was bringing about $500/mo, but now that is completed sells are going up. I hope it would be above $2000/mo for the following months.
I really like the concept, I was thinking on something like this a while ago, but it was around the concept of going out to dinner with someone, sometimes you want to try a new restaurant but your friends are maybe busy or they don't fancy the food, even though you could go on your own, eating alone is not always fun.
If I ever get into a situation where I can't figure out the address, I just pick one of my guesses and bcc all the rest.
Sure, they might think it's a little weird if they notice they're in the bcc field, but it sure is a lot easier than sending off a single email and spending the next few days wondering if it actually went through.
Is super useful, even though It wouldn't give me the email I was looking for, it would show me the "structure" used for emails inside the company:
Based on that I would just guest the email of the person and it used to work perfectly.
I've used this technique a bit, but a word of warning... it's definitely not always the case that all emails in a given firm match "the structure". Usually most of them do, but I have found more than one company with a mishmash of patterns for whatever reason.
Probably the most common thing I've noticed is that "important" people (CEO, etc.) may get a different email, and people with really long name (some Indian names fall into this a lot) may be truncated, or swapped out for just an initial.
Still, other than paying for addresses from Jigsaw or Hoovers, this seems to be about the best approach I've found so far.