Letters of welcome, just as those of farewell, will generally fall under the category of business correspondence, since we will rarely use a written letter for such a purpose with a relative or close friend.
Welcome letters are usually sent to colleagues or employees who join our company, or come to work under our direct supervision. We want to welcome them to the team and to assure them that if they need any special assistance in getting adjusted, we are more than happy to do whatever is necessary.
Often a letter of welcome is written on behalf of the entire team, not just ourselves. Thus, all members of the group will be carbon copied (cc'd) on the letter.
Letters of welcome do not need to be drawn out affairs. However, they should express a friendly attitude and the sincere desire to be as helpful in assisting the recipient with adjusting to their new locale, office environment, or duties. Written well, the letter will also foster an attitude of goodwill among the rest of the team and may even encourage others to extend their own welcomes to the new team member.
As with a letter of farewell, we can turn to many sources for guidance in drafting such a letter. Since it is entirely possible that we could send a lot more welcoming letters than we do farewell ones, we may wish to seek out both online and hard copy sources that can give us guidance in wording such a letter.
The key is to keep the letter short but sincere. As with all business correspondence, we want to run such correspondence through spelling and grammar checking programs to ensure the letter leaves our office as error-free as possible. Especially if the letter is carbon copied to the rest of our staff or even to some of our superiors, a glaring grammatical error that was not caught can prove to be a major embarrassment further down the road.
If you struggle with English, or if it is a second language for you, there are literally piles of resources that can help you word all manner of business correspondence like a real pro - our Business English video tutorials are a great place to start. Just do an online search to put your fingers on those resources that are right for your needs.