Sendmail Question?

Tried to create a regular user called [email protected]. I created it
and saved it.  But I cannot seem to access it anymore nor find the
"postmaster" user anywhere.  Thinking that the user was not created to begin
with; I went back to create another user called "postmaster".  But this time
it tells me that "postmaster" has already been created.  Any ideas?  What
did I do wrong?