I send a fair amount of unsolicited emails from my gmail account to individual business addresses (usually as thank you's, or follow ups to an in person or phone conversation), and sometimes get responses, but very often get nothing at all in reply. How certain can I be that my email didn't get caught in the recipients spam filter. The emails are sent to one person at a time, usually are about 5-6 sentences. I don't want the email to be missed as it is important to the relationships so critical to my business, however, I don't want to be annoying by asking why no reply.