After extensive research on writing to potential PhD advisors, I drafted three messages that I would consider excellent quality-one for each member I was interested in. I briefly introduced myself, hit the highlights of my research interests, and mentioned specific articles or books the professor wrote that I read, which explained my interest in them as an advisor (and I truly did read them).
After three weeks, I have not received a reply. Why am I not hearing back? Is it completely inappropriate to send a follow up email such as "Hello Professor So and So, I sent you an email a few weeks ago about my research interests and asked for a phone or email correspondence about the program. I wanted to touch base and make sure you received that email"?