He neglected to reply to the letter.

他疏忽了回复那封信。

youdao

I'm composing a formal reply to the letter.

我正写一封郑重其事的回信。

youdao

We are writing in reply to your letter of April 5th, in which you asked for our advice concerning the marketing of motor-cycles in the western part of your country.

贵方4月5日来函要求我方就摩托车在贵国西部市场销售一事提供意见，现特函答复。

youdao

The outcome was unclear, a council official saying he sent a letter to the government but got no reply, while other residents doubted a letter was ever sent.

WSJ: On Terror's New Front Line, Mistrust Blunts U.S. Strategy

The fact that Mr Blair did not reply to Mr Salmond's first letter personally is being seen by the first minister as another snub.

BBC: NEWS | UK | Scotland | Fresh protest over Lockerbie row

He said he had yet to receive a reply to a letter he wrote to UK Foreign Secretary Jack Straw four weeks ago on behalf of the British detainees.

BBC: NEWS | UK | Plea over Guantanamo protesters