prevent sending without authorization

[iceruam]

Zimbra 8.6.0
I have lately been seeing emails being sent from my server from names I do not know. test@mydomain.com, frankly@mydomain.com. for example, these accounts do not exist. Is there a way to only allow authorized email accounts to send mail?

Thanks

[phoenix]

Have you checked in your server has been hacked? You also shouldn't be running a version of ZCS that old and no longer supported. Take a look at the thread in this forum a bout recent Hacks and CVE exploits and see if it applies to your system.

[iceruam]

I see no indication of a CVE hack. Tell the boss about running the old version, too cheap to buy a new server then he bitches when we get put on black lists.