Syncing Mail

I'm having this problem where my mail on my macbook pro and iphone are not synced. When I open Mail and check my emails on my mac or iphone, it does not say I opened any of those emails on the other device. I get those emails like I have not looked at them. It is annoying when I only check Mail on one device for a few days and when I open Mail on the other device I get all of these emails I already looked through or deleted. How can I fix this? Thanks!!