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Blocking spoofed address

Posted: Tue May 22, 2018 7:20 am
by manuns
How can i block email that are coming from fake emailer like emkei.cz to my domain. By using emkei.cz we can send email from abc@example.com to def@example.com without any authentication and this seems risk in upcoming days can. How can I prevent this in zimbra 8.6 opensource edition ???

Re: Blocking spoofed address

Posted: Tue May 22, 2018 10:01 am
by stefaniu.criste
Two quick ideas (you need however to find their outgoing IPs)

- you could block their sending IPs at the firewall level (rough and brute)
- you can set a local RBL and add their IPs, as well as other nasty spammers (harder to implement, but very elegant)