no immediate delivery: queued in mailscanner by ACL

[HMStacy]

On a shared server, we have a hotel account with a number of users sending between each other. All of them send/receive successfully except one. They routinely get mail marked as high scoring spam and in mail control it looks like this:



In the exim log we get this:

2023-09-20 11:25:39 1qiz58-0000T5-1J no immediate delivery: queued in mailscanner by ACL

Their originating IP *is* listed in spamhaus, but every other user sending from the same IP is not spam tagged.

We've tried whitelisting their IP and email address in mailscanner settings.

We've added their IP to /etc/virtual/whitelist_hosts_ip and it still is getting spam tagged.

Any wisdom?

[HMStacy]

It seems the user lied about actually having authentication turned on in their mail client settings.
Imagine that, a user lying!