@whynothugo i'm not aware of any tool that actually sends patch attachments from git, i just mean every other mailing list is full of that (i.e. people attach patches when sending, probably via their own tool or just manually doing it. it's commonplace (split between send-email and attachments) in most of the lists i'm subscribed to)
Apparently, #GitLab now supports sending patches by email instead of having to navigate the wizard on the UI[1]. The downside is that they expect patches in email attachments, so no existing tools work because they have a bit of a snowflake implementation.
The whole point of "patches via email" is that it is a transport with a well-defined format for the payload. Using the same transport with a different payload negates all interoperability.