It is odd you cannot access the demos, because I can see both just fine. Anyhow, I shall try and describe how Jax formmailer works, and then you can decide if it is what you are after:
a) you can use any form or the one bundled with the script.
b) there are 4 obligatory fields some of which can be hidden if not needed: recipient, subject, sender name, and sender email.
c) list of recipients appears in a drop down list - no addresses revealed. To allow the sender to select more than one address, just create an alias called ‘everyone’ or similar, and link multiple addresses to it; alternatively, link the alias to a shared address.
d) recipients addresses can be stored in a database (MySQL supported) or CSV text file.
e) administration front-end for detecting script updates and for updating the recipients list. I ditched the whole admin when I did my test install, because I was able to do both tasks easily without needing the web panel.
f) spam/hijack protection via referrer check: the idea is to make sure the script is called by your own form. But I do not know how effective this method is; I hear referrers can be easily spoofed. But I guess it is better than no protection? Ideas, anyone?
g) the only thing I miss is the option to use your own separate response pages (ie. error page, thank you page). I am sure the script can be modified to allow that, but I do not know enough about PHP to do that. If any PHP guru among us would be happy to offer some advice, I’d be most grateful.
h) and lastly, the support documentation could be a bit more detailed.