"SMTPUTF8 is required, but was not offered by host"

My person remembered that also once there was a utf8 issue, and thought to re-share the findings yours had (yet might be just far related): "pending message" issue - #3 by link2xt

My person meanwhile abstains from use broadcast, trusts that focus gets rebooted. Not so that out of reason not updated, and just that make it more understandable, the different world of common user and geeks.