SMG - False Positive, local Good Sender and user Reply as Spam

Hello!

I have a strange and confusing situation (SMG ver 10.5.4-4).

Emails from one of my clients (email sender) are still missidentified as SPAM and quarantined. For me this is normal email communication with footer and some pictures is this footer.

I regularly go to the Quarantine and use option "This is NOT Spam" to inform Symantec of this false positive message.

This week I put this domain to "Local Good Sender" group. It is working for incoming email.

But when my users try to send Reply to users in this domain (previous body is included in new message), emails are identified as outbound Spam again.

Is it possible to make some kind of white list for outgoing domain?

What can I do with this?

Thanks

Peter