Police are appealing for information after four men targeted the post office in Filby this morning.
Post master Adrian Thompson discovered the damage to a door at around 4am when he arrived for work.
He said the whole experience was “unsettling” but that it was “business as usual” at the Main Road premises which opened on time.
Police forensics have been combing the scene.
Officers say CCTV footage shows four men in a car and they are appealing for witnesses who may have seen them acting suspiciously in the area between 2am and 3am.
Mr Thompson, whose family have run the lifeline service since 1963, said it was the first time anything like an attempted break-in had happened.
He said: “When I came to work at 4am I found the damage to the door and that put me on red alert because you do not know what is about.
“We are pretty good here and this is unusual,” he said.
“I do not like this kind of thing here in Filby but there’s no real harm done, we have got to keep the wheels turning.”
Mr Thompson said although the thieves did not get inside he was reviewing security at the post office and a police car would be doing extra patrols.
A police spokesman said officers were keen to hear from anyone who saw a group of up to four men in a car acting suspiciously in the area last night.
Anyone with information should call Norfolk Police on 101 or Crimestoppers via 0800 555111
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