not receiving emails

Suddenly, actually for the second time in a week, I am not receiving emails via my Apple mail function.  I get a message that the mail server "mail.comcast.net" is not responding.  I've been through the account settings, I know my password and have rented and entered it to no avail.  I use the same password and can successfully sign in to my Xfinity account.  I can get emails on my iPhone when in cellular mode.  Condition just appeared, sometime over night.