When an internal message is sent to another account on the Zimbra system, it is tagged as spam. You have to be logged in as a root.
Step 1 – You must work as zimbra user.
To prevent this, run one of the following commands based on your Zimbra Collaboration version:
For ZCS 8.5.x / 8.6.x
Step 2 – You must work as zimbra user. You have to change zmhostname with your hostname in my case I will write linux-sys-adm.com or mail.linux-sys-adm.com
Step 3 – Restart service.
For ZCS 8.0.x
Step 3 – Restart zimbra service..