I have found that the syntax:
$entry["mail"] = "";
Will NOT delete the mail attribute using the OpenLDAP server. You must specify the attribute value to delete it successfully, otherwise you will recieve an "Invalid Syntax" error from the server.
The error: "Inappropriate Matching" will be displayed if the attribute you are trying to delete has no equality rule in the schema. I had a problem deleting the attribute facsimilieTelephoneNumber, and it was because my core.schema file did not have an EQUALITY definition for that attribute. I copied the telephoneNumber EQUALITY rule and it worked perfectly.
