Birthday greetings written by the boss to the following employees. I wrote the title "To My Dear Colleagues". The boss said it was unkind. Please help me think of some other words.

Everything upstairs is fine. You should consider it according to the gender of the employee and the relationship with the boss. If it is a general relationship between the boss and the employee, but it is kind, you can use the method of "dear+little+surname". If you are older, you can use "surname+brother (sister)" or use your first name directly.