A massive, stagnant queue can slow down the entire system. Monitor "stale" messages and purge them if necessary. Conclusion
Catch IP reputation issues before they impact your entire mailing list.
Limitation: It does not store historical data well, making it hard to spot long-term trends. SNMP (Simple Network Management Protocol)
Use the pmta-acct.csv files to look for patterns. If one specific IP is getting deferred while others are fine, that IP needs to be "cooled down" or rotated.