Hmm, I wasn't planning on having a full blown mailing list program in kirby alarm.
I was thinking around just a 1000 character string with each email address seperated by a semi colon. That would give sufficient room for around 20 to 30 emails, but not 400.
For that many I would suggest you use a specialised email program.
for example Group Mail http://www.group-mail.com/asp/common/editions.asp?f=ds
. I think there is a free version where you can send out 100 at a time.
The other possibility is to use an online email service such as dada mail (also free) http://mojo.skazat.com/
This requires that you have a web host and sql server etc. But that is very cheap with the hosting service i use http://www.powweb.com/
Future Mail http://www.futuremail.com.au/
will also do it all for you. I know these guys personally (I used to work right next door to them) and that offer a good all in one solution that may suit. They are based in Perth, Western Australia.
Having said all that, I do have sufficient knowledge to create a mailing list program (if fact I guess you can even try it in the the other program I have written called Kirby Footy. You could enter all the people in your organization and their email address, and then use the bulk email facility)
You can download it fromhttp://www.kirbyfooty.com/html/download.html
If you found the bulk email option in Kirby Footy suited you then I'm sure we could work something out so it was a seperate mailing program that you could then call from Kirby Alarm if you wanted it to be completly automatic. I would be chargeable but I am willing to tailor it to suit your needs.
Anyways, food for thought.