The sender of an email cannot see or hear you while composing a message, so it is easy for him to write something in anger that he would not say to your face. If you encounter such an email, don't take it personally. Reply in a composed and professional manner to avoid escalating the situation. It may be tempting to respond in kind when you feel slighted but focus instead on resolving the problem instead of getting back at the person, especially when dealing with customers.
Think Things Through Before Replying to the Email
Replying immediately after reading an angry email can cause more harm than good. Take your time when responding to an angry email to calm down, think rationally about your reply and figure out the purpose of the email. If the email is from someone who is venting frustration on you or attempting to goad you into a conflict, an immediate, angry retort only escalates matters. Unless the email requires a quick response, such as when an angry customer has a valid problem, compose your thoughts before replying.
Keep Your Reply Brief and to the Point
Be brief and professional in your reply to avoid antagonizing the recipient further. Do not focus on the anger or any abusive comment but address the concern the sender expressed. If the writer has a valid point, such as receiving poor customer service, acknowledge that you understand the problem and assure him that it is being addressed. If the person is so angry that it is hard to discern what upset him, ask for clarification. By being polite in your reply and assuring the person that you will address his problem, you can defuse the situation.
Keep Your Emotions in Check When Replying
Even when the sender of the email makes personal remarks about you, avoid making inflammatory remarks in return; the result is likely to be a heated exchange that won't benefit anyone. Avoid assumptions or personal attacks in your reply, especially if the email is from a customer or colleague. Replying with threats or abusive language can have legal ramifications for your business. This doesn't mean that you have to stand for abuse from the sender though. If he clearly oversteps his bounds in the email, firmly remind him of the implications if he persists in doing so. There is no reason to be threatening, but you should make it clear that abuse cannot be tolerated, as it is not conducive to solving the problem.
Focus on the Problem and Not the Person
By focusing on the problem and explaining to the sender how it can be resolved, you can prevent him from becoming angrier. If the problem is something that the sender did wrong, explain it to him without attempting to make him feel stupid or inferior in the process. If the problem is the result of something you did wrong, own up to your mistake and explain how you will rectify it. In a business environment, don't try to gloss over the problem or shift the blame; instead acknowledge the problem and assure the sender that it will be addressed. Don't make any promises that you can't keep; this only makes matters worse.