Seth Levine receives hundreds of business proposals a year. As the director of the VC firm Foundry Group, he's had to say "no" more than a few times.

Recently, one frustrated entrepreneur lashed out at Levine: "I could have a cure for cancer, you wouldn’t give us a dime. Because you don’t know us, you don’t anyone who knows us, and in my case, I’m too old." The person, who Levine keeps anonymous, accused him of biased disinterest and of not even looking at the plan.

The exchange inspired Levine to offer some helpful ideas for entrepreneurs feeling the burn of one too many rejections. Here are three takeaways to keep in mind if you're starting to get frustrated:

Remember: It's Not Necessarily You

An idea may be great, but not for the firm you pitched it to. Levine's company sees thousands of plans each year, but typically invests in fewer than ten, which means that they have to be picky. Understanding the audience and the investment focus of a potential backer can prevent a lot of heartache and anger.

Save Your Feelings for Your Friends 

Levine vented on Twitter about the exchange. While most responses supported him, some tried to justify the behavior:

"Rejection can be soul crushing for lots of folks, especially if yours was no. 100. Anger might be the only emotion s/he has left," John Minnihan wrote.

This may be true, but it shouldn't affect your pitch. Acting calm, cool, and collected (even if you're just acting) will get you more than letting your anger take charge. 

A Response Can Be an Opportunity

The good part of being rejected? If you handle it gracefully, it might open the door for future conversation. Levine has had companies that he initially rejected stay in touch, update him on their progress, and seek advice ... and his firm has ended up investing in some down the line.