🚀 go-pugleaf

The only part of our proposal which it would be very valuable
if all list expansion tools implemented is the loop controls,
both the creation of loop control info and the use of it for
loop controls. Apart from that, our proposal is intentionally
written such that it could incorporate existing activities. Even
those existing lists which are not willing to implement loop
control could be handled, by just ensuring that they will not
be part of any loops.

I agree with you that it would be much neater to add RFC822 header
fields for loop control. However, I do not believe this is possible.
The reason for this is that the proposal should work also under
X.400, and since CCITT seems to be firmly determined to put distribution
lists in the P1 layer, there is very small changes of getting
them to accept new P2 facilities for handling mailing lists.