1. A method for sending an electronic mail message in a communications network, said message comprising a header and a body, said header comprising at least a first field adapted for containing an address of a sender of said message, and a second field adapted for containing an address of a recipient of said message, said sender being a user identified in said communications network by means of a first identifier associated with at least a second identifier, said header further comprising a third field, containing said first identifier of said user, said method comprising the steps of: selecting said first identifier of said user from said third field of said header; requesting said second identifier associated with said first identifier from at least one apparatus of said communications network; including said second identifier in said header of said message; and forwarding said message to said recipient; said step of including said second identifier in said header comprising including said second identifier in said first field, wherein said first field is a sender field of the electronic mail message.