Code fences with
~~~ have been supported in the forum since at least 2017:
However, when replying by email the reply trimmer truncates messages on
~~~ lines, likely mistaking them for delimiters. For example, sending the literal source text
Prose before fenced code. ~~~ Fenced Code ~~~ Prose after fenced code.
results in a post containing just “Prose before fenced code.”. Using a fence of back-ticks works fine.