Is it bad business etiquette to begin an email with "Hi, <name of person> " My boss saw this, because i copied him on the email, and he yelled at me for saying "Hi" I guess it's not professional enough? The recipients were lowly peers, not big-wigs :(

Assuming this was a business email account, all emails are property of the business, and can be used in official documents and such-like at any time. Your boss wants to make sure all of your emails are a positive reflection on the decorum of his office.

Your boss is a pompous moron for jumping on you for that, especially if you were emailing peers. And you cal tell him that "Hungry Guy" from Answerbag said so!

In a business relationship it's best to start by saying Dear so and so. Hi means you are on friendly terms with a person and is used on a casual basis. Business is never casual.

I usually steer clear of using "hi" in professional correspondance unless I am e-mailing a co-worker or contact that I am relatively friendly with. In any case, whether or not something is appropriate is decided by your company and it seems they deem it unprofessional.

Professional enough? Omg

Yes, it isn't correct business etiquette. I don't know why your boss would yell it to you though. Still it is good advice and you should take it.

I like to start with "Hello", but I know that the correct way to do it is to say "Dear___". But to me "Dear" is too affectionate so I just say "Hello".