all the email filtering services tally the bits of evidence it sees, so the littlest thing can trigger over, and I can see ZENWorks topics contributing just a bit that way.   Still doesn't stop the need of confirming the new basics of the reputability of your Domain in properly committing to where it sends email from, which is what the whole SPF, DKIM, and DMARC are all about.   Your other emails may be close to the cusp of being blocked in many places, so making sure those settings for your domain is important.

I have this issue with one supportcase (first line Zenworks), all email to that specific case get tagged as potential phishing mail and bounce.

As far as I know first line is third party and got there own mail systems, but even mail to support_case get tagged and bounces.

At the same time I got like 7 or 8 other cases going where I don't have issues replying to support emails.

/Lennart

If your email is being blocked (and even notifies you it's as spam) it could be you've been caught in recent changes of what is considered acceptable email system standards.

Have your email administrator check your system's SPF, DKIM, & DMARC configurations to make sure they are up to the newest standards of compliance. i.e. to have them, and that they don't allow others to use your domain.  I am seeing increasing failures for even having the 'soft fail' settings used.