This past few days I've been unable to receive email on my custom domain tiersman.com

MX records are set to the correct settings as far as I can tell. The name-servers recently were changed, and there were multiple records (two NS that were correct and two that were old/needed to be removed). Mail sent to the email address @ the domain.com are not delivered or come back saying there is a delay.

EDIT:

Email is being received correctly from outside-sources such as commercial companies, however no mail is being received from Hotmail accounts including the same account that is unable to receive mail. Oddly, I have other domains with no issues.