Let the phone ring...
Hi Phil,
I sent Craig an email last Monday. I then followed up with a phone call two days later. He answered the phone rather quickly (~4 rings). He had indeed received my email but probably got distracted on the reply. We discussed the changes and hung up. About a minute after hanging up, I called back and the phone rang ~8 rings before picking up.
I've discovered that a follow-up phone call after a couple of days is, in general, always a good thing. I'm not calling to complain, but just to see if they got the email, did they have any questions, etc. So far, it's always been a pleasure talking to vendors.
Take care,