It was originally my intent to put all recipients in the Bcc: header and use the -t option. But then I read in RFC 2822, "Internet Message Format", (http://www.faqs.org/rfcs/rfc2822.html) the following:
--- begin quote ---
Section 3.6.3 Destination address fields
[snip] There are three ways in which the "Bcc:" field is used. [snip] In the second case, recipients specified in the "To:" and "Cc:" lines each are sent a copy of the message with the "Bcc:" line removed as above, but the recipients on the "Bcc:" line get a separate copy of the message containing a "Bcc:" line. [snip] Which method to use with "Bcc:" fields is implementation dependent [snip].
Section 5. Security Considerations
[snip] When the second method from section 3.6.3 is used, the blind recipient's address appears in the "Bcc:" field of a separate copy of the message. If the "Bcc:" field sent contains all of the blind addresses, all of the "Bcc:" recipients will be seen by each "Bcc:" recipient.
--- end quote ---
Not at all the desired effect for a mailing list application!