Most of the time the patent attorney that files the patent will also perform a patent search. Inventors should deal directly with a patent attorney, so that they are the direct client. Learn how to file your own patent, so that you are familiar with the process. For example, read books on the process. Some patent attorneys specialize in specific types of patents - and depending on the complexity of the product, this may be important with some types of products like technical or electronic.
Company submits inventions to industry.
Any of those mailings that don't get returned as undeliverable, normally just get tosssed in the trash by companies that receive the mailing. Find out what your full range of options are. Find out which is the best for you, then find a vehicle to showcase your invention to the right audience, for example, a trade show, or a web site, or a publication. But make sure that whatever vehicle or company you choose has a track record, and experience in showcasing inventions, as well as targeting the right audiences - this is a rare combination. Company promotes inventions to industry.