Final answer:
A congratulatory letter to a former colleague should show happiness for their achievements and be written in a warm, sincere tone. It should be appreciative and personal, and leaving contact information is a thoughtful gesture.
Step-by-step explanation:
A congratulatory letter to a former colleague should show you are happy for their achievement or success. It's essential to maintain a professional but warm tone throughout the letter. While writing such a letter, one should be appreciative of the relationship and experiences shared with the colleague. There's no need to remind the colleague of past situations where they were less successful; it's both impolite and irrelevant. Furthermore, a congratulatory letter doesn't necessarily have to come from a manager; it can be written by anyone who wants to express happiness over the colleague's accomplishments.
Begin the letter with a friendly and courteous greeting, such as "Dear [Colleague's Name]," and proceed by expressing sincere congratulations. Your letter should come across as personal and heartfelt, rather than relying on standard phrases that may appear disingenuous. Moreover, be sure to leave your contact information to stay in touch, which can also signal your willingness to offer continued support and maintain a professional network.