Caution: News Letters
The easiest way to really piss off all of your subscribers to the full extent is to send a News Letter with all email addresses in the "To:" or "CC:" field of the email.
Never, never, never (and did I mention NEVER?) do this!
Apart from the fact that it is completely annoying to have a big message header in an email, I'm sure none of your subscribers like the idea of their email address being shared with everybody else.
Having all email addresses in the "To:" or "CC:" field can also start a chain reaction in case anybody decides to hit the "Reply to all" button: Somebody else will yet again "reply to all" asking everybody to stop using the "reply to all" button, which in term will cause three more users to "reply to all" and ask why they get all these emails, and what this "reply to all" feature is, that everybody is talking about…
You get the picture: It is VERY dangerous and it shows that you either don't know what you are doing, or that you have no respect for the privacy of your subscribers.
User the "BCC:" field (and only your own email address in the "To:" field), or use a bulk-mailing software, that automatically BCCs everything for you.

Be careful with mailing services: Email addresses are the gold of the Internet age, and a lot of services (especially free ones) are just interested in your customer email-database. I strongly suggest, you keep your data as close to you as possible, and you don't allow anyone do the job for you.