I have an idea and I'm trying to develop it, however when it comes to receiving feedback from companies, I am not getting a response. They don't even notice me. I know they need my product as I encountered this problem many times in the past with many websites. How should I approach them? How do I know if they would use my product or not?
I've worked for years in business to business sales and consulting.
You need to find out who works or makes decisions in a company in the area that your potential product could be useful, ie customer service. LinkedIn could be useful for this.
Call them on the telephone. Don't e-mail. Open the conversation by asking for help, 'Hi, I'm wondering if you could help me find the person who would be responsible for customer service? I'm looking to get feedback on an innovative new idea I'm considering developing that may be useful to your company.'
The most important thing you could ask them during the call is whether they've ever identified the problem that you're proposing to solve as an issue themselves. If they've never noticed, or don't care, then your new product will have a more challenging sales cycle since you'll have to do a lot of education. If they already know they have a problem, you'll need to act quickly because they may be already looking for a solution.
Best of luck.