People change jobs for a variety of reasons, including promotions or relocation to another town or state. You have filled a position at work for a certain period of time, and you have done the leg work to find a well-qualified replacement. You want her to transition smoothly and get off to a good start, but you also want others to have preliminary information about the person who is taking your place. Writing a letter of introduction requires a little forethought, as you want to list characteristics you feel are worthy of note.
Draft a list of bullet points on scratch paper that you want to include in your letter. Use these points to refer to later. Include items like basic personality traits that you feel are pertinent, as well as job skills for the work at hand.
Open your letter with Dear ____ and include managers, CEOs, or the primary person or people you will be addressing. You can also write to the key figure and cc (carbon copy) the rest. Mention how you have enjoyed your time at the company, but you will be departing on a certain date. Note how you have taken your time and gone through a careful candidate selection process to find the person most suitable to replace you.
Add the details about your replacement in the body of the letter. Refer to your notes earlier and write sentences in one or two paragraphs which highlight her expertise. An example would be: "I'm pleased to introduce Charlene Mitchell, who moved to Oakland from New York 2 years ago. Her interview won me over because I could see her quick wit, her abilities in communication, and her sharp resume." (Add a few items.) Mention the personal elements, such as a hobby or extra talent. (She's traveled the world and speaks fluent Italian.) Write using a somewhat business-like tone, but in your own style. The people there know you already, so you have some freedom in how you express yourself.
Add a line or two about how you have complete confidence in your replacement being the best choice for the company. Note matching points between the replacement's attributes and the company's needs.
Sign the letter with a cordial line of departure, then "Sincerely" or "With my regards," and your name. Date it and offer any contact information where you can be reached in case anyone needs you during the new person's transition period or if questions arise. Submit the letter to all concerned parties in print or distribute it as an email by following the usual company procedures.
Keep your letter upbeat and focused on the positives.
If you are leaving due to some disagreements or discomforts at the office, use caution when writing an introduction about your replacement and your departure. It is probably best to exclude the details regarding your tenure at the company and your departure and leave on a good note.