Postfix logging extractor

Hi, I am new with graylog
I redirect syslog postfix log to graylog and I find difficulties to search for example a sent email from the beginning to the end as in every MTA gets new ID (I configure streams)
Any advise please? How to perfectly exploit postfix wit graylog?
Thank you,

A post was merged into an existing topic: Daily Challenge: Postfix logging extractor