When joining to a mailing list, one can, and should, use a unique name for each list. Any mail to that address must have come via the list. Mailing list software should be upgraded to support such addresses. One can even create a new address for each letter and thus track messages associated with a given conversation. The address field is just a text string and the only requirement is that it is able to pass through intermediate systems.
All family members can get email addresses without artificial constraints.
You can also register whimsical names. Email addresses can be used creatively. For example, by tagging a name used to subscribe to a list, the source of the address can be identified even if it the address is hidden in a secondary mailing list or passed on to a third party. Better management of email addresses, such as by adding a signing value, makes it easier to identify unsolicited mail. Each mention of one's address in a discussion can get a unique tag.