Naylor has been hauling a "steady stream" of mail up the private drive to their home in rural Berkshire ever since the Nov. 16 engagement announcement.
"The post they've had is absolutely incredible, from all over the world," he tells PEOPLE. "There are lots of well-wishers, sending cards and presents."
And though the dress remains a tightly kept secret, the address is perfectly straightforward. Try 'Kate Middleton, Bucklebury'. "Absolutely right," chuckles Naylor. "And some of it's just addressed to Kate Middleton, England, but it still gets here surprisingly."
"There was one this morning to 'Mike and Carole Middleton, Parents of Catherine Middleton, Bucklebury, Berkshire," he says as he jumps into his red van and heads out again on his rounds. "I joked with them about it. I said, Look! It still gets through. What a good postman you've got!"