Very simply, you respond cordially and promptly, letting them know that although you have just closed a round and are not currently fundraising, you would like to keep them updated on your progress, as there might be future opportunities for them to be involved. If you have the bandwidth, offer to meet with them briefly to give them the ‘public’ part of your pitch, and then make sure they’re on your mailing list for announcements, press releases, etc.  You never know when you’ll be raising money again, and it never hurts to have an investor who is already familiar with the company.

*original post can be found on Quora @ : http://www.quora.com/David-S-Rose/answers *