A letter of resignation can be the ideal way to leave a job with class and dignity, but, as an employee, you still need to be careful what goes into the letter, especially when stating the reason for the resignation. If the reasons for the resignation are honourable and understandable, stating what those reasons are should not create any problem.
Relocation is an acceptable reason for leaving a job. People can relocate for any number of reasons that have nothing to do with their job, and any employer should understand that. Perhaps the employee's spouse was forced to relocate for a job. Maybe the employee needs to be closer to his family. The employee might like the job, but not where she is currently living.
Returning to School
In times of a struggling economy, returning to school after several years in the workforce is an increasingly attractive prospect for many people. Having a college degree can make anyone a more valuable prospective employee, and leaving a job to pursue more eduction is perfectly understandable. The employee isn't resigning because of job dissatisfaction, but out of a desire to better himself. Returning to school also leaves the door open for said employee to return to a company with a better education and more opportunities for advancement, something that may benefit the employer.
Another reason for leaving a job that is usually safe to put in a resignation letter is a desire for a career change. Stating that you are unhappy with a company shouldn't go in a letter of resignation, but wanting to embark on a new career is a valid reason. An employer could be fair and provide a positive work atmosphere with an outstanding salary and benefits, but that may not be rewarding if a person simply doesn't enjoy the company's field of work. A desire for a career change is by no means a slight against an employer.
A Better Offer from Another Company
Many people leave a job because they received a better job offer from another company. While most employers should see that as a valid reason for a resignation, stating it in a letter of resignation can be tricky. The key here is to keep the letter positive. The departing employee should be careful not to insult her employer -- either intentionally or inadvertently -- and thank the soon-to-be-ex employers for the time spent with the company. The company may also make a counteroffer to its employee to get her to stay. The counteroffer could lead to better advancement opportunities, a higher salary or better benefits.