I’m using port 587 with STARTTLS and haven’t encountered any errors when testing just now…
also in Stalwart-mail’s logs it seems to be using TLSv1.3 and not running into any errors…I do have a slightly unusual config that I’m testing (using pebble to run a local ACME server and using a .test domain name, but that probably isn’t enough to break/fix anything…)
I’m not using “Override TLS options” in the port 587 listener…