By coincidence, I had an experience of this kind of thing in a completely different context yesterday - I use Mailchimp from time to time to send out group emails to members of a local organisation, inviting them to meetings and letting them know what's going on. The manager passed on a message to me from one of the members complaining that he'd never been invited to any meetings in his 5 or 6 years of membership, so he didn't think he was on our mailing list.
When I looked into it I found that not only was he on the Mailchimp list, but he had a 100% open rate for the emails I'd sent out, ncluding one earlier this month. So yes, sometimes people don 't just ignore emails but conpletely block them out of their minds.
Yes, there's reality, and then there's what's going on in people's heads. This is why a small number of people who have signed up for my newsletter complain that I'm spamming them. At some point, they forget they signed up.
I've also seen it work the other way (people "remembering" things that never happened). For instance, when I was teaching, I once had someone leaving voicemails for me on the school voicemail system during the summer, when I wasn't around to check it. When I got back, I listened to the first two, followed by a third that said something like, "Why aren't you returning my call? I've left you twenty messages." Meanwhile, the principal had gotten a voicemail that started out with, "I've left Mr. Hiatt a hundred messages." Probably, there was some rhetorical exaggeration here, but when I called the person back, she really did seem to believe that she'd left more messages than she actually had. Of course, she was a parent who seemed oblivious to the existence of summer vacation, so there's that, too.
Human memory is a funny thing.