yours faithfully、yours sincerely、(尤用於美式英語的)yours truly是信末最常見的敬語,用於正規的及半正規的書信均可.
正確的格式是在信的開頭用Dear Sir/Madam(即不認識收信人),則信末用yours faithfully,而在信的開頭用Dear Mr/Mrs/Miss/Ms Smith(即知其名而不熟悉者)則信末用yours sincerely/truly.
In English a "yours sincerely" or even a simple "regards" would suffice; French-style floridity survives, just, only in the context of diplomatic correspondence.