Angela Thirkell 
The Brandons [EPUB ebook] 

“I wonder who this is from, ” said Mrs. Brandon, picking a letter out of the heap that lay by her plate and holding it at arm’s length upside down. “It is quite extraordinary how I can’t see without my spectacles. It makes me laugh sometimes because it is so ridiculous.”
In proof of this assertion she laughed very pleasantly. Her son and daughter, who were already eating their breakfast, exchanged pitying glances but said nothing.
“It doesn’t look like a handwriting that I know, ” said Mrs. Brandon, putting her large horn-rimmed spectacles on and turning the letter the right way up. “More like a handwriting that I don’t know. The postmark is all smudgy so I can’t see where it comes from.”
“You might steam it open and see who it’s from, ” said her son Francis, “and then shut it up again and guess.”
“But if I saw who it was from I’d know, ” said Mrs. Brandon plaintively. “In France and places people write their name and address across the back of the envelope so that you know who it is.”
“And then you needn’t open it at all if you don’t like them, ” said Francis, “though I believe they really only do it to put spies from other places off the scent. I mean if Aunt Sissie wanted to write to you she would put someone else’s name and address on the flap, and then you would open it instead of very rightly putting it straight into the waste-paper basket.”
“You don’t think it’s from Aunt Sissie, do you?” said Mrs. Brandon. “Whenever I get a letter I hope it isn’t from her; but mostly, ” she added, reverting to her original grievance, “one knows at once by the handwriting who it’s from.”