A handful of deleted icloud mail message keep reappearing in my inbox

On February 17 & 18, 2015 I deleted about six or seven email messages from my iCloud mail inbox. I don't recall whether I deleted them from my iPhone, my Mac, or from iCloud online (on a work PC). In any case, these messages have been continuously redelivered to my inbox ever since, as often as ten or more times a day. No matter how often I delete them again or empty my Trash, they keep being redelivered.

Anyone had this experience or know how to stop this increasingly annoying beha