Erin Hudson's daughter caught it all on camera when they noticed the unusual thief last Sunday.
Hudson said it is not uncommon to spot yearling heifers by their house - and they get out of their pen on a regular basis.
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But Hudson said she had never seen the animals go through the mail.
"I hope it was nothing important," she can be heard saying as the cow makes a run for it with a buddy.
She said after they shooed the animals away, they apparently returned and knocked the entire mail box over in a ditch.
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