Techniques for exchanging internal electronic mail over an open data network within a collaborative communication system are disclosed. The exchanging of the internal electronic mail does not rely upon an email address commonly known to include an @ sign. Each of registered users in the collaborative communication platform is assigned an identifier. The identifier is used for delivering the internal mail so authored similarly to a traditional email, except that the internal mail is delivered without relying upon an email address or the domain name therein. The identifier of a recipient cannot be used as an email address for someone other than any of the registered users to send a message to a user in collaborative communication system.