SMTP auth param long ago changed to boolean option

Actual auth method is automically-determined from the server.

See Ticket #13042

horde/config/conf.xml

@@ -1386,14 +1386,10 @@
       (Sending mail via port 25 is DEPRECATED.)"/>
       <configstring name="localhost" required="false" desc="The local hostname
       / domain [localhost]"/>
-      <configenum name="auth" desc="SMTP authentication">false
+      <configenum name="auth" desc="Authenticate to SMTP server?">false
        <values>
-        <value desc="No authentication">false</value>
-        <value desc="Best available authentication">true</value>
-        <value>DIGEST-MD5</value>
-        <value>CRAM-MD5</value>
-        <value>LOGIN</value>
-        <value>PLAIN</value>
+        <value desc="No">false</value>
+        <value desc="Yes">true</value>
        </values>
       </configenum>
       <configstring name="username" required="false" desc="The username to use