Switched server, some people are not getting e-mails
 

I moved my website onto a new server last tuesday and I am still having people complaining about not getting e-mails. I am getting them just fine and I believe the majority of people are getting them just fine. But there are some that are not. I run 3.8.7 and want to know what maybe I should check to see why they are not getting their e-mails? Their profile is fine.