The message being sent is the default.mailtpl, probably two in
conjunction: SIGNUP1 and &SIGNUP
You can either modify those and put them in your listname.mailtpl
or turn them off in your listname.mailtpl, like this
PUT listname.MAILTPL PW=xxxxxxxx
>>> SIGNUP1
.QQ
That should prevent the default SIGNUP1 from being sent. Or, you can
edit the $SIGNUP template to your taste and put that in your
listname.mailtpl
This is covered in chapter 9 of the manual, if you have a copy.
Douglas