Emails usually are not as formal as letters.

The subject line is not so important as the body of the email.

CC means "clear copy".

CC copies to all concerned makes work processes easier.

BC means "blind copy".

The addressee in the CC-line is not visible for other recipients.

The greeting "Dear" plus a surname is used for a very formal email.

A greeting is not necessary in an informal email.

There is no difference between a formal and an informal greeting.

It is important that it is immediately clear what the purpose of the email is.

Not further details are needed after stating the purpose.

The call-to-action should be included in a seperate paragraph.

A sign-off is not necessary in informal emails.

Acronyms may not be used in a formal email.