Here’s an interesting finding by email specialist Yesware: if you’re sending an email to two people, you’re more likely to get it opened and receive a response if you put one person in the “To:” field, and the other in “CC:”.
Why is this? Well, it could be that if you put both in the “To:” field, a psychological observation called “diffusion of responsibility” comes into play – address something to a group of people equally, and everyone assumes (hopes?) that the others will take action. Indeed, it’s been said that you’re more likely to get a response if you send an email to one person and CC it to another, than you are if you send it to the main recipient alone. This is because the main recipient feels they’re being “watched”.
You Could Increase Your Email Reply Rate 12% By Doing This One Simple Thing on the Yesware blog.