To:
In this line, you write the e-mail address of the person to whom you
are sending a message.
Cc:
means carbon copy. A carbon copy sends a copy of an e-mail to another
person. This feature is useful when you want to send an email to several
people at once. Another use for carbon copy is when you wish to send
yourself a copy of the e-mail. You must separate addresses with a comma
when you put more than one address in the cc line.
Bcc:
means blind carbon copy. A blind carbon copy allows you to send a copy
of an e-mail to another person. Blind carbon copies are different from
carbon copies because they do not show the receiver that the message
was "copied" to someone else. You must separate addresses
with a comma when you put more than one address in the bcc line.
Subject:
In this line, you should write a description of the message. You may
leave this line empty but often people do not read e-mails with non-descriptive
or missing subject lines. Examples of descriptive subject lines are:
Happy Birthday, Thinking of you, Wishing you well.