UEM is capable of sending emails. UEM is capable of telling your email server to send multiple emails. UEM is not cabable on its own to send multiple emails. It needs a server and SMTP server to send emails, and as such won't work if you simply tell it to send a million emails at once (or even a couple thousand probably unless you have a very robust email server).
People have used UEM to create a mass emailing system by combining it with DataAssist and creating a system where emails can be sent in bursts to a couple of hundred users at a time. Your ISP probably has strict limitations in the number you can send per second, minute, or day that you would have to be careful not to exceed.
Any mass email application you build would at some point send an email. WAUE can be used to do that. The applicaiton would have to be built by you and it wouldn't be as simple as telling WAUE to send as many emails as you want and it will be done. There will be limits and you would have to work around them... usually by offering a way to send emails in batches.