As much as you want to give your employer a piece of your mind, it's best to not write an angry resignation letter when you quit. You can control what your boss and your co-workers think about you long after you've left your position by the way you tender your resignation. Still, you may someday endure a work experience so awful that you just can't keep silent about it, and you can only express your feelings through your resignation letter.
When you're leaving a job that you truly enjoy, you might be tempted to write a long letter that conveys a sincere message that you'll miss working there. But even in the best of circumstances, your resignation letter needn't contain anything more than your name, position and the date on which your resignation becomes effective. To write the perfect resignation, you could say, "Please accept this as written notice that I am resigning from my position as manager for ABC's marketing division, effective May 1, 2013. Thank you."
If you insist on writing a letter to express a negative opinion about your working relationship, it will obviously be longer than the typical resignation letter. Still, keep your letter to one to two pages -- any longer than that and you may lose the reader's interest or the impact of your letter. Besides that, you may give the reader the impression that your letter is just a rambling, emotional rant.
An angry resignation letter actually can contain constructive feedback. You're expressing your dissatisfaction; therefore, rather than simply penning a gripe-filled letter, take the opportunity to give the company ideas about improvement. Draft your letter, put it down and review it with fresh eyes several hours later or the next day. After your anger subsides, you might take on the final draft with a different perspective that still expresses your anger yet communicates your disappointment and dissatisfaction.
If you believe an angry resignation will give you the satisfaction of letting your manager or the company know how you really feel, give constructive feedback the company can use to improve. Avoid name-calling and profanity, and state your concerns in their order of importance. For example, if your manager's micromanagement was worse than the employee benefit package, describe your manager's shortcomings near the beginning of your letter.
An angry resignation letter will become your epitaph. Any professionalism your boss and your colleagues thought you had will instantly be erased by the tone of your letter, which could color the perception of the terms on which you resigned. If you submit such a letter, when another employer asks if you left on good terms, the answer would be "no." You probably aren't planning to reapply for your job anyway, but your personnel file might be stamped "ineligible for rehire."
An alternative to an angry resignation letter is an exit interview. Many companies conduct exit interviews to obtain valuable information about an employee's opinion of the company. Ask if your company will conduct one with you and make sure to ask if the exit interview is anonymous, confidential or both. If it's anonymous, it means that your name won't be attached to any of the comments; if confidential, the HR department will act on your comments without disclosing your precise statements.