https://aria-net.org/SitePages/Portal/Bridges.aspx has fixed almost all the papercuts with Bifrost from the XMPP side
That’s an interesting strategy. I chose to have https://git.singpolyma.net/cheogram-smtp live behind a mailserver instance on the same box just to handle any SMTP edge cases, etc, but speaking the SMTP directly does probably give a bit of control.
I’ll stick with the proper bidirectional gateway, but this is an interesting second option.