That is to say, three letters.

When you included (by request) "positively no letter writing" in my holiday menu, you did not make it plain who it was that was positively not to write.

So, although she tells me sadly that she expects no answers, Aunt Caroline positively does.

I may say at once that I know all the news.
On the other hand, there is some news which Aunt Caroline does not know.

Owing to your embargo on letters, I have not been able to inform my Aunt of the progress of my book, nor of my discovery of the perfect secretary.