How to protect for send mail by telnet on port 25?

[alexai]

Hello all,

I have problem for my mail server in my office so i am using Zimbra Collaboration 8.5

Problem:
when i used the telnet program for send mail, but i can sent mail by no login in any user

How to solve this issue? Please help me.

Thank you so much.

[liverpoolfcfan]

I believe it should refuse to send the email if it is not from one of your trusted networks or not from a user on your server.

[DualBoot]

If you send mail by telnet to your domain manage by your server, it should work each time. That the way it is.

[imanudin11]

Hello all,

I have problem for my mail server in my office so i am using Zimbra Collaboration 8.5

Problem:
when i used the telnet program for send mail, but i can sent mail by no login in any user

How to solve this issue? Please help me.

Thank you so much.

Hello,

You can improve your Zimbra server with "sender must login". Please check the guidance from this link : https://imanudin.net/2014/09/07/how-to- ... imbra-8-5/ or this one : https://wiki.zimbra.com/wiki/Enforcing_ ... ername_8.5