It's beta. It's for .NET 1.1. You're on your own. (but you can always ask.

Just type in these fields in your body text:

[memberId]
[memberName] or [memberText]
[memberLoginName]
[memberPassword]
[memberEmail]

And member profile fields can are merged too. If you've defined a field with an alias
of "address" you can just use it as: [address

When sending a testmail - If the address is found on
a member, then the member data is merged.

The zipfile comes includes a readme.pdf .. check it out and head on to Umbraco Forums for more