For a lot of reasons, you don't want to try sending mail to every address you've harvested from your inbox. First of all, some addresses are probably personal, and you might not want to send your business newsletter to everyone in your family. Next, many addresses that appear on your list are administrative addresses. Finally, some of the addresses are no longer valid. Avoid sending newsletters to bad addresses else you will have to deal with bounced messages. A list of addresses harvested from your inbox, can roughly contain a third bad. We suggest that the first thing you do is verify the addresses using a tool like Email Verifier. eMail Verifier verifies every e-mail address on your list list, allowing you to determine up to 80% of "dead" email addresses.
Unfortunately, verifying the addresses using a tool isn't enough. Unless your addresses came from a customer database, you probably want to manually remove all administrative addresses such as orders@ anything, support@ anything, listserv@ anything. There are more, but that's a good start. If you don't remove these, then you'll receive automated replies from a lot of places. When you're doing the manual clean up, you can also remove any personal addresses to which you don't want the newsletter going.
Once your list is clean you can send a message to it. It is recommended to send a unique message to each recipient using your regular SMTP (simple mail transfer protocol) server. If you have more than about 200 messages to send, this will be quite slow if you don't use an automated tool like MaxBulk Mailer.