Editing Rejecting false "mail from" addresses

     Rejecting false "mail from" addresses
1.-Zimbra Collaboration 8.5 and above 
Please use the next commands to increase the security and reject the logins for users that doesn't exist in the LDAP: 
     zmprov mcf zimbraMtaSmtpdRejectUnlistedRecipient yes 
     zmprov mcf zimbraMtaSmtpdRejectUnlistedSender yes 
     zmmtactl restart 
     zmconfigdctl restart 

2.- For Zimbra Collaboration 8.0.x and previous 
       Open the file /opt/zimbra/conf/zmconfigd/smtpd_sender_restrictions.cf and add this line into the middle of the file, prior to the tag_as_foreign.re lines: Add this: 
       check_sender_access hash:/opt/zimbra/conf/domainrestrict 

It should look like this.. 
check_sender_access hash:/opt/zimbra/conf/domainrestrict 
%%contains VAR:zimbraServiceEnabled antivirus^ check_sender_access regexp:/opt/zimbra/postfix/conf/tag_as_foreign.re%% 

3. Zimbra Collaboration 7.x 
You should follow the next steps: 
      su - zimbra 
      zmlocalconfig -e postfix_smtpd_sender_restrictions="reject_unknown_sender_domain, permit_mynetworks, permit_sasl_authenticated, check_sender_access hash:/opt/zimbra/conf/domainrestrict, permit" 

4.-Remaining steps are same for ZCS 8.0.x and previous versions 
 i.-Create the file "/opt/zimbra/conf/domainrestrict" and add your domain(s) to it. 
       
localdomain.com   REJECT 
       anotherlocaldomain.com   REJECT 
ii.- Create the hash database of "/opt/zimbra/conf/domainrestrict". Run as 'zimbra' user. 
         postmap  /opt/zimbra/conf/domainrestrict 
iii.- Restart zmmtactl. 
        zmmtactl stop 
        zmmtactl start 

5.- Testing 

 i.- Make following connection from a non-local host which is not part of mynetworks. 
        telnet ZCS_server_address 25 
         mail from: user@localdomain.com 
         rcpt to: user2@localdomain.com 

ii.- You should get following error at the rcpt command if you used the Zimbra Collaboration 8.6 steps: 
          550 5.1.0 <hi@example.com>: Sender address rejected: example.com 
iii.- You should get following error at the rcpt command 
           554 5.7.1 <user@localdomain.com>: Sender address rejected: You're not me!