We've been using 37 Signals https://launchpad.37signals.com/signin https://launchpad.37signals.com/signin, which has worked great and we send emails constantly

We've been using 37 Signals https://launchpad.37signals.com/signin https://launchpad.37signals.com/signin, which has worked great and we send emails constantly (saving docs/files with a date for easy reference)