When you should you use the To-field
* When there are less than 5-10 recipents.
* When everyone you e-mail know each other.
* When there is a reason for everyone getting the e-mail to
know who else gets it.
A good example is when John sends an e-mail to invite 5
people to a meeting at work. It is probably good for the
others to know who have been invited to the meeting.
A bad example is when John is holding a course or an event
for 50 people, and sends information to everyone. They
never agreed to have their e-mail addresses sent to
everyone else, when signing up just to him. Another bad
example is when John e-mails everyone of his work contacts
or friends to tell them about his new job.
Things to consider:
People usually enjoy knowing who are
invited to a party for example, if you are inviting 5-15
friends who all know each other. But you might want to keep
the list private and friends might not like to have to
explain why they didn't come, to other people afterwards.