How-to add E-Mail addresses or domains to Zimbra's Spamassassin whitelists
https://wiki.zimbra.com/wiki/King0770-Notes-Whitelist-Spamassassin-MTA

Do this a zimbra user

sudo su - zimbra
touch /opt/zimbra/data/spamassassin/localrules/sauser.cf

Edit sauser.cf file, and add the following (the example includes options for an individual E-mail and a full domain)

vim /opt/zimbra/data/spamassassin/localrules/sauser.cf

Example

whitelist_from jsmith@exampledomain.com
whitelist_from *@exampledomain.com

Restart amavis

zmamavisdctl restart