Have you ever thought how much email has changed the world? Maybe you haven't... Email appeared along with the Internet and cell phones and the latter two were bigger than life themselves so it was easy to overlook email... By the way, why "email" and not "e-mail"? The printed media still sticks to "e-mail", but the inconvenience of typing the hyphen is too big and omitting it is too simple. Hence, "e-mail" is fast turning into "email". Actually, this symbolizes the essence of email: eliminating most of the inconveniences of previous types of correspondence like letters, memos and faxes and simplifying them.
Let's talk about business email specifically. It is transforming workplace communication in a blink of an eye. Before email business correspondence was formal by definition. Nowadays not only email messages are less formal than say business letters, but business letters themselves are using plain English. And the fact that the same people who write email messages write business letters is one of the reasons why. It's impossible to communicate in email as if you were speaking to the person you're writing the message to and then turn around and write a letter using pompous ambiguous phrases that don't sound right. Our minds just don't function that way.
So, email has made communication more immediate, colloquial and intimate. Some people can't stomach it insisting that professional correspondence needs to remain formal. Choosing the right degree of formality for email is not an easy thing though. And the ability of email to allow for almost instant communication sounds wonderful but it can work against you if you are not careful. Email is such a convenient tool for the sender that he/she often forgets about the recipient. At the same time, email provokes the feeling of urgency in the recipient and most of us feel obliged to respond to the messages as soon as they are received. And imagine what pressure people who get 200-300 emails a day are under! No wonder email bankruptcy is becoming common. There's another extreme: some of us also become addicted to email and check it while driving, on vacation and in most unusual places.
Email etiquette rules are still evolving and sometimes we're confused in dealing with email. But the most basic rule, the one that we tend to forget is: show in your email messages respect to the person you are communicating with. Remember, you can't retrieve the sent email.
Email hasn't ousted business letters and memos. Business letters are still being used when something more or less formal should be communicated and needs a signature. Memos are nowadays very often transmitted by email but they still remain a separate distinct type of business correspondence and will in the nearest future. Faxes are merging with email and fax machines are becoming obsolete because of the Internet faxing.
One thing is for sure: email has become the most widely used type of business correspondence and has tremendously influenced all other types of business correspondence, mostly to the better.