当获悉某人晋升或是在事业上取得巨大成就时，应该打个电话或是写封便签祝贺。这种友好往来对建立和巩固友好的商业合作关系大有益处。
here are some principles that congratulatory letters follow:
1. the purpose of writing the letter is to make your reader feel certain that he or she deserves the special message of recognition and praise.
2. the note should be brief, dealing with the primary topic only. these messages are most effective when they conduct no business.
3. the whole message should carry a tone of being positive and conversational.
4. be sure to send the letter within a few days of the event. any delay in delivery of the message would make your effort worse than no effort at all.
下一次，我们将给大家分析一些祝贺信的实例，别错过哦。
（《国际商务写作教程》，对外经济贸易大学出版社 英语点津 annabel 编辑）