E-mail Ownership

Who owns e-mail messages on an organisation's system?

This is the common question, but it is not necessarily the right question.

An e-mail message that an employee wrote himself is a work of authorship and as such the rules of copyright apply. In general, if the employee wrote the message as part of his duties for his employer (i.e., 'in the scope of their employment'), the employer owns the copyright.

If the e-mail was not part of the employee's duties (something personal or related to another activity, whether permitted by the employer or not), then the user has copyright, but the employer, as owner of the system on which it was created or passed through, may have some rights to the copy on the system.

If an employee is forwarding a message written by someone else, the issue gets even more complicated. For instance, does the original author have the right or the intention to authorise any forwarding?