Thought I'd post this script, it's written in Coldfusion, so it won't be of much use to some of you but, maybe you can find a way to write something in PHP or .. you might move to a host like mine that runs on Unix and supports both CF and PHP :)
It's a rough piece but it only took me a couple minutes and seems to be working. I'll refine it over the next couple weeks. If you want a later version, let me know.
This script, sets an application variable application.newuserid which is the highest user uid at the time that it ran. The next time it runs it checks for userids that are higher and then puts a welcome message into their inbox using the "privmsg module". Also, I have already edited the privmsg.module so that "Receive daily e-mail for unread messages" is checked by default.
This script relies on CFSchedule function to trigger it and I have it set to run every 1800 seconds, though might make it run more often as I rely on it more. Also, I have it emailing me everytime it runs... again this is just until I'm ready to let it run on its own.
select uid from users
where uid > #application.newuserid#;
forum for more information.">
INSERT into privatemsg (author,recipient,subject,message,timestamp,newmsg,hostname,folder,author_del,recipient_del,format)
VALUES ('adminsid',"#i#","Welcome",'#message#','','1','admin','0','0','0','1');
#i# - sucess