Harassing Stalking Obscene Email from a Zoho User. 'Mark Spam' not working

Harassing Stalking Obscene Email from a Zoho User. 'Mark Spam' not working

I keep receiving an alleged obscene email from another zoho account. 'Mark Spam' does not seem to be having any action. Is that emails from Zoho are whitelisted in toto?  

Tried to verify the IP Address. Zoho emails do not seem to be carrying valid sender IP addresses. 

Pl. clarify on this front. I believe this is the third major incident reported where Zoho Antispam Engine is failing miserably.