This is actually two-questions-in-one :

Is it possible to sync LDAP attribute fields which have multiple values into different OX fields? I'd like to have the 3 first mailAlternateAddress values (if any) synced as email1, email2 and email3.

This leads to the second related question : We have issues with people using addresses which only exist in mailAlternateAddress when adding attendees for events. OX currently considers them as external participants (and everything goes bad from there...). Would the above fix this by having OX relate those "email aliases" to the right users?