The limit is 1000 recipients.
The limit is 1,000 recipients, although I expect you could increase this by including another email list in as one of the recipients… I’ve not tested this as my clients have never needed to!
We roll our Google Apps for our clients as a matter of course; it’s FAB for enterprise-level email management, but if you plan to use it for email marketing or newsletters, please can I recommend PHPList? It will manage your database with ease, comply with Spam regulations (double opt-ins, allowing people to unsubscribe etc) and is free to use!
I’ll put a link to more info below…