There's good news and there's bad news.
The good: you've received only 100 rejections.
The bad: expect more.
Sadly, that is the reality of the post 1990s publishing market consolidation: a handful of key people where there was plenty.
Folks, you do not need an agent to get published (my example proves it), but it is becoming a Catch 22: more and more publishers will not accept anything from writers directly - submissions and queries must come from known literary agencies.
Trouble is... agents consider writers their worst enemy. Why? Because majority of writers do not make enough money to make the effort of selling their works worth while. What an agent wants is a Tom Clancy, someone who manufactures mega sellers so they can sit back and cash in cheques for nothing.
Imagine this scenario: an employer calls you and offers you a job - basically to cash in a cheque. What do you do?
Now look at it this way: you (the employer) offer a literary agent to sell your book and receive a cut from sale. What is an agent's reply? Some will send a bitchy reply to never-ever bother them again. Many will blacklist your IP / email address. Majority will ignore you (it makes no difference whether you query by email or snail mail, except that you will save money by emailing because despite assurances that all mail is responded to if an SASE is included - it is simply not so.)
Folks, there is no miracle way. Query, query, query... When an agent does not reply or when you receive a rejection without any explanation (95% of rejections) and you can't figure out why :
- re-send you query again after some weeks
- try another person from the same company
- change your subject line
- re-write your query / synopsis - concentrate on different aspects of your novel (make it sound more gory, or sexy, or political, or controversial, or change the genre it falls under...)
Finally, if you are only considering sending out your first query letters let me give you this advice: expect to receive rejections. Trust me, it will be that much easier to bear when you know they will be coming. They will be coming.