How to filter out audit id field from Brightmail logs in Splunk?

Hi Splunkers: I have an issue filtering out a field called **Audit ID**. Each email is assigned this number as it passes thru a mail exchange, so the conventional wisdom would be that if I search on one Audit ID, but we are getting several audit id results from other event records. I have created transforms to deal with various event records containing mailing activity such as mail delivery, accept, order, sender, subject, trackerid, verdict etc. I want this audit id field to be only indexed by Splunk for verdict ID and ignore all other event records. This audit id field exists on the other event records pertaining to mail delivery, accept, order, sender, subject, trackerid etc. How do I filter this field in Splunk so that it only shows this field 'audit_id' from 'verdict' event records and not others. Thanks Mohammed