Authenticate users using their firstname

[Fady AL HAYALI]

Hi,

I'm setting up a Postfic and Dovecot with LDAP email server. My users in LDAP 
is like this:

    dn: uid=firstname,ou=People,dc=domain,dc=com
    uid: firstname
    uidNumber: 4025
    gidNumber: 4025
    givenName: firstname
    objectClass: top
    objectClass: person
    objectClass: posixAccount
    objectClass: shadowAccount
    objectClass: organizationalPerson
    objectClass: inetOrgPerson
    loginShell: /bin/bash
    homeDirectory: /home/firstname
    cn: firstname lastname
    mail: firstname.lastn...@domain.com<mailto:firstname.lastn...@domain.com>

This is how I connect Dovecot with LDAP

    hosts = ldapserver
    ldap_version = 3
    base = ou=People,dc=domain,dc=com
    deref = never
    scope = subtree
    user_attrs =
    user_filter = (&(objectclass=inetOrgPerson)(uid=%n)
    pass_attrs = uid=user,userPassword=password
    pass_filter = (&(objectclass=inetOrgPerson)(uid=%n))
    default_pass_scheme = SSHA

When I enter a user's email address and password as the following:
email: firstname.lastn...@domain.com<mailto:firstname.lastn...@domain.com>
password: password

and according to my setting which I used "%n" as you see above, the username 
used to authenticate is "firstname.lastname". I checked the Dovecot variables 
but I couldn't find something useful in this case to manipulate the "%n" 
variable.

I would like to keep using email addresses as 
"firstname.lastn...@domain.com"<mailto:firstname.lastn...@domain.com> but 
authenticate users using their first name. I really hit a wall here and any 
help will be much appreciated.