RBL Whitelisting with zimbra postfix

 RBL Whitelisting with zimbra postfix 

Cause: Genuine IP is being Blocked by the RBL.

RBL - Real-time Black hole list.

Common RBL providers - BarracudaCentral, SpamHaus.

When you find any genuine email blocked reason as smtp blacklisted/ip blacklisted in log messages then it can be whitelisted with zimbra postfix as explained below.

Note: If sender domain / IP is blacklisted with global RBL, it might be affected by suspicious infection. Hence try to find the reality and then proceed accordingly. Whitelisting affected senders might increase chances of your domain also getting infected. 

Resolution:

    1. Create a file postfix_rbl_override in /opt/zimbra/conf/

    2. Add the IP/Domain Name to be whitelisted in the file /opt/zimbra/conf/postfix_rbl_override as shown below,

##

192.168.1.5   OK
Domainname.com OK

##

    3. Issue the postmap command as below ,

## postmap /opt/zimbra/conf/postfix_rbl_override

    4. In the smtpd_recipient_restrictions.cf file include the following lines, just above the line reject_unlisted_recipient

check_client_access hash:/opt/zimbra/conf/postfix_rbl_override

check_recipient_access hash:/opt/zimbra/conf/postfix_rbl_override

Note: For 8.x the file is located in opt/zimbra/conf/zmconfigd/smtpd_recipient_restrictions.cf

And for versions below 8.x you should edit the file /opt/zimbra/conf/postfix_recipient_restrictions.cf

After making changes restart the zimbra mta service.

## zmmtactl restart