Hi,

mailForwarding could be a solution for a per-user install.

1) In my case, some users of domain abc.com have their mailbox on my iredmail server, other users of this domain are exchange users. mailForwarding is indeed a good solution but we need to use another 'private' domain like abc.local for this forwarding. I know that something like :
test@abc.tld                smtp:[my-exchange-server]
in /etc/postfix/transport works great but i can't find  how to do this with iredmail and ldap backend.  Maybe something with mtaTransport ???

2) I've other domains xyz.tld which exclusively use exchange. I'm looking for a way to relay all incoming emails for this domain to my exchange server. I've tried with mtaTransport attribute but it doesn't work.

Any help is welcome.

And Thx for the good work

Sorry, per-user transport map is not implemented yet. but i commited the code moment ago:
http://code.google.com/p/iredmail/sourc … 09404787db

It's easy to implement it, steps:

* Make sure 'mailUser' objectclass is able to use 'mtaTransport' attribute in /etc/postfix/schema/iredmail.schema (in the bottom line):

objectclass ( 1.3.6.1.4.1.32349.1.2.4.3 NAME 'mailUser'
    DESC 'Mail User' SUP top AUXILIARY
    MUST ( mail $ uid )
    MAY ( storageBaseDirectory $ mailMessageStore $ homeDirectory $
        userPassword $ mailHost $ mailUID $ mailGID $
        mailQuota $ mailQuotaMessageLimit $
        mailForwardingAddress $ accountStatus $
        userRecipientBccAddress $ userSenderBccAddress $
        enabledService $ telephoneNumber $ backupMailAddress $
        mtaTransport $ memberOfGroup $ lastLoginDate $ lastLoginIP ))

* Add per-user transport map lookup file in postfix main.cf:

transport_maps = ldap:/etc/postfix/ldap_transport_maps_user.cf, ldap:/etc/postfix/ldap_transport_maps.cf

* Copy /etc/postfix/ldap_virtual_mailbox_maps.cf to /etc/postfix/ldap_transport_maps_user.cf, change 'result_attribute= mailMessageStore' to 'result_attribute= mtaTransport'.

* Restart postfix.

Note: value of 'mtaTransport' in domain object is still 'dovecot', change mtaTransport in mail user object.

Enjoy, and don't forget to share your success story