Jennifer Schwalbach Smith strengthen the relationship. This is a major benefit, as strong relationships lead to excellent networking. Not only does a congratulation letter make others feel good, but it can also be rewarding in the future when the recipient may be in a position to help you advance in your career.Professional and personal life changes, accomplishments and promotions are all crucial milestones in a career. Taking the time to celebrate your business relations for their achievements with a letter of congratulations is an excellent way to strengthen your relationships and network.Your words of congratulations contribute to the spirit of the occasion and remind the one receiving your text, email, or card that their life event is being celebrated by someone who cares about them.