It’s not an open relay.

a) qozz.com should set their rejections to FAIL, not blackhole. Blachole fails silently and may “fail” poorly written relay tests since it won’t outright reject the mail (but it also won’t deliver it).

root@server442 [~]# cat /etc/valiases/qozz.com
*: :blackhole:

Instead they should set:

*: :fail: No such user here

Blackhole appears to be the default for most domains on this server. I recommend switching them all to fail if you are being marked as an open relay.