It's possible (that) he has not received the letter.

可能他还没有收到那封信。

《牛津词典》

It's a written letter not a conversation, but the principle is the same.

这是一封写好的信而不是一次谈话，但它们的原理一样的。

youdao

He noted, with some irritation, that the letter had not been sent.

他指出那封信还没有发出去，有点生气的样子。

《牛津词典》

He also knew how police think. So,he did not hide the letter where he knew they would look for it.

VOA: special.2009.12.26

He said, my apologies for not answering your letter but my health is poor and--but it was a long letter.

他写道,非常抱歉没能及时回复,我身体欠佳,这是一封很长的信

耶鲁公开课 - 金融市场课程节选

So he signs the letter and then he writes underneath it, "The Gestapo has not harmed me in any way.

他签署了文件，并在下面写到，“盖世太保从不曾伤害我。

耶鲁公开课 - 心理学导论课程节选

If they are not the same letter, then why has the existence of the November 12 letter not been acknowledged by the ECB and the Irish Department of Finance?

FORBES: ECB Secret Letter to Ireland To Be Released?

Doggett's office had not seen the letter and did not have an immediate comment.

FORBES: Down On The Farm Bill

He perceives the sorts of steps needed to ensure the durability and effectiveness of our deterrent as contrary to the spirit, if not the letter, of his denuclearization agenda.

CENTERFORSECURITYPOLICY: Stopping START