Rust is not a magical language. It's just got the right features to be a C replacement, which is mostly: a simple type system (much simpler than C++'s or Java's) that has the right extensibility (traits, no inheritance) and can have an ABI that programmers can reason about due to monomorphization (no v-table dispatch).
All the borrow checker stuff amounts to: just enough pain that to avoid it you must design better APIs.
Yep, after reading the post I'm not any less impressed by (or interested in) Rust. If the post's claim were "Wait until Rust changes more slowly before investing more heavily in it," I might be able to agree.
For a project like notqmail, I would worry about portability. qmail runs on a lot of platforms and getting Rust bootstrapped is a bear.
For any new MTA/MSA you don't need to run on old HP-UX systems. You can elect to only run on systems that support Rust, which is to say: all the modern OSes.
Rust is not a magical language. It's just got the right features to be a C replacement, which is mostly: a simple type system (much simpler than C++'s or Java's) that has the right extensibility (traits, no inheritance) and can have an ABI that programmers can reason about due to monomorphization (no v-table dispatch).
All the borrow checker stuff amounts to: just enough pain that to avoid it you must design better APIs.