Article in English: Even if you are writing a "formal" email, how formal that email is depends on the person who's receiving it. For instance, you wouldn't use the same level of formality when writing a professor that you would when applying for a job. When you're first contacting someone, it's better to be more formal than you need to be, just to be on the safe side. Do some research to dig up the person's name if you don't already know it. Knowing the person's name makes the greeting seem more personable, even while you are employing formal techniques for your email. If the person has emailed you already, it's fine to copy their greeting style. For example, if they use "Hi" and your first name, it's acceptable to reply in the same style, by using "Hi" and the person's first name when you address the email.

Summary in Hindi:
तय करिए कि आपको कितना औपचारिक होने की आवश्यकता है: व्यक्ति का नाम पता लगाइए: उस व्यक्ति की लीड (lead) को फॉलो करिए: