Please reply by return.

请尽快回复。

youdao

If we don't receive a reply by tomorrow morning, I shall have to get on to him.

如果明天早上我们得不到答复，我们还得和他联系。

《新英汉大辞典》

We trust that you will be able to accept our offer, which shall be kept open against reply by wire.

相信贵方能接受我们的报价, 此盘有效期可到回电为止。

youdao

People who think they could do the job could reply by text message or on their cell phones.

VOA: special.2009.02.02

Sussex reached 11-0 in reply by the time more rain forced an early close.

BBC: Martin-Jenkins gives Sussex edge

Kent began their reply by putting on 32 for the first wicket before Matthew Fleming departed for 15.

BBC: Thrilling tie in Cardiff

Durham had reached 84-2 in reply by the close, with an excellent chance of building a big first innings lead.

BBC: Durham pacemen too hot for Hants