Comcast Email Issues - Incoming emails can sometimes take from 1-6 hours or even more to be delivered

I am experiencing significant delays in receiving email, very sporadically for the past two weeks. An incoming email can take from 1-6 hours or more to reach my inbox, as confirmed by the time stamp.  The sender is in my Comcast address book.  The emails are not landing in my Spam folder and the sender's domain is not blocked.  I have the same sender sending emails to my Gmail account and I always get them within minutes of them being sent.   Delays were not always a problem.  I used to get the emails within 10 minutes of them being sent out.  Did you make changes to your email server protocals late April/early May?   The senders email address is: [Edited: "Personal Information]   These are important business emails and I am unable to respond in a timely manner due to the delays.  Thank you for looking into this issue and hopefully providing a resolution.  DRD