A message of congratulations should include a salutation, congratulatory wishes, reflections on the individual and expressions of support. The message should finish with a reiteration of the congratulations and a closing.
The exact format of a congratulatory message depends both on the occasion and the writer's relationship with the recipient. Some common occasions for sending messages of congratulations include a new job, an anniversary, a promotion, an engagement and the birth of a child.
The writer starts with a salutation appropriate to their relationship. Directly afterward should be the first expression of congratulations and how the writer heard of the news. For instance, writers can indicate hearing about an engagement through a mutual friend and follow up with "Congratulations on your engagement."
For a longer letter, the next part of the message consists of reflections on how the person got to that point. For example, the writer can acknowledge hardships the recipient faced. The letter can also concentrate on attributes that led the recipient to success.
The next part includes an expression of confidence and support. For example, the writer can indicate a desire for a marriage filled with love and laughter. The message should include a second congratulations worded slightly differently, perhaps by using "I'm so happy for you" instead of "Congratulations." The writer then closes and signs the message.