Here is what I do for mass mailings:

> everyone who has an account on a particular system.  I plan to build a 
> big file of email and SMTP commands using PERL and getting the info from 
> the database from the app.  Then I will just dump that file on the mail 
> server.

===============SHELL SCRIPT===============
#!/bin/sh

for email in `cat mailing-list.txt` ; do
 echo "From: whoever@us.pason.com (Sender's Name)" > asdf
 echo "To: $email" >> asdf
 cat mass-letter.txt >> asdf

 cat asdf | sendmail -fwhoever@us.pason.com $email
done

rm asdf
===============SHELL SCRIPT===============

The mailing-list.txt should contain valid e-mail addresses, one per
line.

The mass-letter.txt should contain a From: line and a Subject: line,
(and other headers if desired), then a blank line, then the body of
the message.

This will not work for extremely long lists because you will run out
of argv space in the shell expansion of the `cat mailing-list.txt` .
We have used it successfully for a couple of thousand addresses.

There are no SMTP commands necessary if sendmail is properly configured
on the system.  You can just send each message to sendmail's stdin and
it will take care of the dirty work.

The benefit of doing a mass mailing this way is that each message is
individually customized for the recipient, with the recipient's e-mail
address in the To: header.  This makes it more likely to pass a spam
filter.  For example I check all the To: Cc: etc. headers of mail sent
to me for instances of the string "ockers" and if that is not found,
then the mail is spam-suspect.  (So, Valuable.Customer@ is not something
that will get through my spam filter.)

Naturally I hate spam and would never be party to spamming.  We use it
for service notifications for our application service provider systems.
(I.e., the server will be down on such-and-such a date for the 
installation of more disk space, etc.)

-- 
Jim Ockers - Pason (ockers@pason.com)
Contact info:  http://www.pason.com/ockers.html

Fight Spam! Join CAUCE (Coalition Against Unsolicited Commercial Email)
at http://www.cauce.org/ .