I won’t have my letters to Hannah

“Flavia, dear!” she [a postmistress] said. “What a pleasant surprise. Why, you’re all wet! I was just thinking about you not ten minutes ago, and here you are. Actually, it was your father [a philatelist] I was thinking of, but it’s all the same, isn’t it? I’ve a strip of stamps here that might interest him: four Georges with an extra perforation clean through his face. Hardly seems right, does it? Quite disrespectful. Miss Reynolds over at Glebe House bought them last Friday and returned them on Saturday.
“’Too many holes in them!’ she said. ‘I won’t have my letters to Hannah–‘ (that’s her niece in Shrophshire, dear) – ‘being seized for infringement of the Postal Act.’”
She handed me a glassine envelope.
“Thank you, Miss Cool,” I said. “I’m sure Father will appreciate having these in his collection, and I know he’d want me to thank you for your thoughtfulness.”

**
What’s the meaning of the highlighted?