Check your spam folder often.
I do it at least weekly and find that about one in fifty pieces of "spam" is not spam.
I once designed and wrote computer code and occasionally "designed or wrote a bug into my software".
If your email software deletes spam at regular intervals, check your spam folder more often than that.
I have this happen sometimes and I also find many discussions I was not aware of when I come to this site. There are many times I try to post and Ning is acting up as well.