9.1.2.6 Handling LDAP Errors

At this point the resulting URL is used to perform an LDAP search. If an LDAP error of some kind occurs, processing terminates with a temporary failure indication (4xx error in SMTP). If the LDAP operation succeeds but fails to produce a result, the catchall address attribute for the domain retrieved from the LDAP_DOMAIN_ATTR_CATCHALL_ADDRESS MTA option is checked. If it is set, its value replaces the current address.

If no catchall address attribute is set, the smarthost attribute for the domain retrieved from the LDAP_DOMAIN_ATTR_SMARTHOST MTA option is checked. If it is set, an address of the form

@smarthost:user@domain

is created and alias processing terminates successfully with this result. Additionally, the conversion tag for the domain obtained from the LDAP_DOMAIN_ATTR_CONVERSION_TAG MTA option will, if present, be attached to the address so that conversions can be done prior to forwarding to the smarthost. If no catchall address or smarthost exists for the domain, processing of this alias URL terminates unsuccessfully.