please be informed /please inform...

please be informed 係被動語. 相反 please inform 係主動語. 被人通知就梗係被動啦.

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We would like to inform you that .......

Each expression has a particular ‘tone’ and this should be taken into consideration whenever you write. Being too direct to your superior, or being too polite to your subordinates can send the wrong signals, so it is important to think about the direction of communication when you write.

http://www.business.gov.hk/bep/opencms/release/chi/business_writing/index.jsp