Struct.new(:name, :route, :mailbox, :host)
Net::IMAP::Address
represents electronic mail addresses.
Returns the phrase from [RFC-822] mailbox.
Returns the route from [RFC-822] route-addr.
nil indicates end of [RFC-822] group. If non-nil and host is nil, returns [RFC-822] group name. Otherwise, returns [RFC-822] local-part.
nil indicates [RFC-822] group syntax. Otherwise, returns [RFC-822] domain name.