Dear Guilhem, I reported #815805 months ago, so I tracked down here to this ticket.
It seems that you already defined the "mail-cmd" interface before, did you have a chance to proceed further? If you have alpha level implementation on hand, please kindly share out, and I can help to test then improve it. I feel email sending of caff is one of most significant barrier for new debian contributor to get deeper involved. Let's speed up to improve this. Thanks for your understanding! Cheers, -- Roger Shimizu, GMT +9 Tokyo PGP/GPG: 4096R/6C6ACD6417B3ACB1