In Outlook you can create a Distribution List: From MS Outlook Help:
"A distribution list is a collection of contacts (contact: Person, inside or outside of your organization, about whom you can save several types of information, such as street and e-mail addresses, telephone and fax numbers, and Web page URLs.). It provides an easy way to send messages to a group of people. For example, if you frequently send messages to the marketing team, you can create a distribution list called Marketing Team that contains the names of all members of the marketing team. A message sent to this distribution list goes to all recipients listed in the distribution list. You can use distribution lists in messages, task requests, meeting requests, and other distribution lists."
Using this, create an email account say email@example.com. With this account, in the Name Field, put Newsletter Recipients (or something like that) then send the newsletter to Newsletter recipients and BCC the Distribution List. Your only limitation is how many emails your host allows you to send at once. if necessary, create multiple lists. This is actually a handy feature.
Type Distribution List in the help menu of Outlook for complete details.