This has happened a couple times recently. I am subscribed to a thread, I get an email notice of a new post, I click the link and the post is not there.
I can understand that this might happen in a controversial thread where some posts are getting deleted between the email and the time I access the thread, but a few of these were not of that type at all.
This thread specifically:
EEStor Ultracapacitor May Be Real
I have rcvd two email updates in the past few days, but neither appear. They didn't look like spam from what I could tell.