Ok, the reason I mentioned the other blog was that I was wondering if perhaps it was a WordPress issue since it is also a WordPress blog.
However, since that time, I have found the source of my problem. The AnHosting.com support has been helping and found that for some reason SBCGlobal is blocking their emails from their hosting site. So, when WordPress sends email notification of a blog comment, that email sent by the hosting company is being blocked by SBCGlobal.
This is also curious because the secondary blog that I mentioned is hosted by yet another hosting company, but their emails must be being blocked by SBCGlobal, as well.
An email to SBCGlobal has been sent requesting explanation of the reason they are blocking emails from the hosting site and also requesting the issue be resolved by *unblocking* the emails.
This was not an issue of my having inadvertently blocked emails, but rather my ISP blocking them for some reason from my hosting service.
If you would like, I can let you know what SBCGlobal says when I hear back from them.
Thank you for your assistance and have a good evening.