underscore in handle gets deleted/filtered
an underscore in a handle like _abc_@example.com gets deleted/filtered, resulting in _abc@example.com, thus unmentionable handles (Hubzilla - Mastodon).
an underscore in a handle like _abc_@example.com gets deleted/filtered, resulting in _abc@example.com, thus unmentionable handles (Hubzilla - Mastodon).