It would be possible to create a simplification for the creation of multipart/report messages with a Mail::Message::Construct addition, but it will probably not give much gain: it is simple to create with generic multipart features, and reports are rarely seen (as far as I know)

RFC6533 defines a few message mediatypes, to be used for these report multiparts. For now, it looks too application specific to implement generic support for this.

When we would support report generation, then probably via a separate CPAN module. Anyone interested in this feature?