I couldn't find a clear answer in the Microsoft Office help files (big surprise there), nor on webpages. I asked the I.T. department. They didn't think there was a way to do it, except maybe through some complicated method involving Mail Merge. So I investigated, and through the Mail Merge hint, and the murkiness of the Help files, I finally came through with a concrete set of instructions that do in fact work. So if you use Outlook and need to perform this task, here they are. I put this here as a public service. I still hope there's an easier way, however.
Sending email to multiple people, while making it look personalized for each, without disclosing the entire recipient list: A tutorial
1. Enter all the recipients as contacts in Outlook under a temporary subfolder.
a. Make a subfolder by clicking File, New, Folder and giving it a name.
b. Enter each contact individually or import the contacts from a Sellen database.
2. In Outlook, click your subfolder to view its contents, then click Tools and select Mail Merge. This will bring up a new box.
3. In the new box, make the following selections:
a. Select “All contacts in current view”
b. Select “New Document” if you have not written your letter yet, or "Existing Document," and then "Browse" to select the letter if you have written it.
c. Select “E-mail” under the Merge To heading at the bottom of the box. You will be prompted to enter a subject line for the email.
d. Click OK. If you selected “New Document”, Microsoft Word will open for you to type your message. Begin doing so by clicking “Edit Mail Merge Document” on the Microsoft Office Assistant that comes up.
4. Optionally, you may use Mail Merge fields to personalize the message; for instance, "Dear <
a. Click "Insert Merge Field," at the top of the document
b. Select "First name” (or any other merge field you prefer).
5. When you are done typing your message in Word, click "Merge" at the top of the document. Make sure under "Merge to" it says "Electronic mail," and then click the "Merge" button. Word may tell you that "A program is trying to access email messages you have stored in Outlook," and ask you if you want to allow it. Click "Yes." (NOTE: You may have to click "Yes" twice for each recipient.)
6. The messages will be sent, one at a time to each recipient, and will be stored in your "Sent Items" folder in Outlook.