Server Administration :: Alert Email Notifications?

I'm trying to set up alert notifications. I have to program it myself, because SE isn't allowed to do it with OEM. As far as I can see from the documentation, this should be all that is necessary:

conn / as sysdba
exec dbms_aqelm.set_mailhost(mailhost=>'127.0.0.1')
exec dbms_aqelm.set_mailport(mailport=>25)
exec dbms_aqelm.set_sendfrom(sendfrom=>'alert@noreply')

[Code]......

but this gives me:

ORA-24940: invalid combination of ANONYMOUS namespace, default presentation and
e-mail receive protocol
ORA-06512: at "SYS.DBMS_AQ", line 737
ORA-06512: at line 11

I must be missing something! Probably something very basic. There is nothing in any trace files.