We are currently getting a lot of complaints of bounceback emails from our server. It is not for all email addresses, only some but for the ones who it occurs all the time.
The message we receive is:
[188.8.131.52] #<[184.108.40.206] #5.0.0 smtp; 5.3.0 - Other mail system problem 550-'5.7.1 Sorry, message looks like spam or phish to me (OP)'
We have disabled both the Spam Filter and AV temporarily and it still occurs.