'90s ISP shenanigans Show more
I once did some consulting for the national ISP of a small island nation. Their mail servers were getting bogged down and they wanted me to make sure they were tuned correctly before adding more hardware.
When I investigated, I found that the bottleneck was SpamAssassin. I also discovered that most of the mail waiting for SpamAssassin scanning was outbound. Ah hah! It was misconfigured! So I reconfigured their mail server to only scan inbound email. Problem solved!