1. You have to subscribe to it 2. The interface for finding old issues can be bad (like long densely-packed threads with no search feature) 3. It forces me to manage my inbox (well, that's my problem)
They can all be solvable though. I never used sourcehut - are these all the same issues?
If it's a mailing list then surely the mail is searchable using your choice of mail client?
(and that means new contributors get the worse experience.. not ideal)
(Also for example SourceForge only gives mbox files to administrators, not to regular users [0])
[0] https://sourceforge.net/p/forge/documentation/Mailing%20List...
Well, it is not perfect, much still, the hassle is one-time, so meh.
Threads can also be downloaded individually.
And the search function is decent(ish) in the web interface.