Shotgun,
I have never had an ATT email address that I know of but presume that it is similar to AOL.com, Yahoo.com, etc., in that there will be a folder/directory for new mail that passed whatever SPAM tests are by default set up and one for new mail that the server ID'd as SPAM and maybe/probably some other folders that may have never had anything put into them. Depending upon what the default time for keeping mail ID'd as SPAM is, all of the emails from Hpbby-Machinist are probably in your ATT spam trap. So in the words of the immortal Pogo, "We have met the enemy and he is us.".
What you need to do is to log into you ATT.com account with your browser, go to your spam trap, and if you find the missing messages there, mark them all as Not Spam.
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