Five years after the first line of code, Stalwart v1.0 is here: the first stable release, with a finalised database schema, months of profiling and stress testing, a rewritten search engine, and benchmark results that put it ahead of Postfix and Dovecot in 35 of 38 tests.
I would like to see someone compare it against On-Prem Exchange, for no reason other then it’s stupid to compare.