"We're sorry to say we couldn't accept your proposal for funding.
Please don't take it personally, because most of the proposals we
rejected, we rejected for reasons having nothing to do with the
quality of the applicants. For example, we were very reluctant to
accept proposals with only one founder, because we think starting
a startup is too much work for one person. We also had a higher
threshold for applicants who were still in school, groups where one
or more members planned to keep their current jobs, and groups that
couldn't all move to California. We rejected a lot of proposals simply
because we couldn't understand them, or didn't understand the problem
domain well enough to judge them, or because the project seemed too
big to start on only three months of funding. Sometimes we even
rejected good ideas, because another group proposed the same idea
and seemed further along.
We realize this process is fraught with error. It's practically certain that groups we rejected will go on to create successful startups. If you do, we'd appreciate it if you'd send us an email telling us about it; we want to learn from our mistakes.
Thanks,
Y Combinator Staff"