Emails from some automated senders never come to me.

Automated emails, like password reset links or newsletters I subscribed to, never show up in my inbox.  I don't remember the full list of senders this has happened with, but DC comics.com, tor.com, and MySpace.com (just today) all come to mind.  I've also had intermittent problems like this with my bank, Ally.  I always check my spam folder, but those emails are never there.  I've also tried bypassing my email program, Thunderbird, and going directly to the Xfinity website to check my email there, but the emails aren't there either.

What should I do?