Feature request

Hi,

I operate roundcube on a larger server with possibly groing amount of users - therefore I'd like to cover my back and have roundcube add an X-Originating-ip header or something equal to outgoing messages, in the same way that yahoo and hotmail do (actually gmail doesn't do this and this is getting them blacklisted by spamcop all the damn time).

Having the ability to add such a header will allow me better to track abuse of my servers and would make roundcube more usable in larger deployments. I'd appreciate it if this feature will be considered ;^)

Auke