Oliver is having trouble looking for his type writer so he can write a letter to The Postmaster General complaining about the poor service of the Hooterville Post Office. Lisa and Eb cause him to get so frustrated, he ends up having a "temper transom".
From the episode "Old Mail Day" season 4, episode 8. Originally aired November 20, 1968. Episode description from imdb.com : "It's "Old Mail Day" as Sam Drucker hands out letters that have gotten misplaced in his post office. He delivers one letter that dates back to 1917. Having learned nothing from his previous letterwriting fiascoes, an upset Oliver complains to the Postmaster General for delivery service. The locals soon turn on Oliver because Drucker's General Store is never open; his letter got the Hooterville post office reclassified and now Sam's always on his bicycle delivering mail."
—Jay Phelps, imdb.com
https://www.imdb.com/title/tt1061225/

Link to another clip I uploaded from the same episode "Old Mail Day"    • Green Acres  Old Mail Day (Part 1 of 2)  

Part 2 of the same clip    • Green Acres  Old Mail Day (Part 2 of 2)