Totally false!! Look it up! Mixes like that are perfectly safe up to at least 6 mos. if they're kept cool and dry. We've used them after with no loss of flavor, and definitely no toxic mold!
Just another false thing that has been tossed around to try to scare people.
People with extreme allergies have to be careful with 'any' foods, (dated or not), otherwise stamped dates are 'best by', 'sell by' dates only. This goes for most any dates on foods. Look up Duncan Hines statement as well as other legitimate internet sites.
People are constantly passing around as truth things that have no basis of truth to them. Best to find out from truthful sources instead of just accepting scare emails, etc. Please don't spread false rumors.