In my Projeqtor I regularly have errors from users who fail authentication :
** ERROR ** cause = ldap_bind() [function.ldap-bind]: Unable to bind to server: Invalid credentials

I wanted to see quickly if there are any "real" errors in my logs, but any grep is polluted by these ldap_bind errors.

Is it possible to set these as a warning, or trace ? Then it would make it easy to see immediately if there are actual errors begin raised.

Ticket #1343 recorded.

Note: an extra option would then be to have an automatic email to the site administrator whenever there is an error logged... Would that be possible ?

Not sure it is a ggod idea, as you may have some recurrent errors that will spam admin.
If you reammy nedd such a functionality, a syslog listening to the log file could do the jiob.