Better Unix Through System Graphs
Unix people tend to be comfortable in their non-visual command-line world. But sometimes a picture says an awful lot:
Read that as “around 11:40, someone sent a mass e-mail through the server. It took twenty minutes to process, peaking at 916 deliveries per minute.”
What’s more, the vast majority of the deliveries were successful, and some failed. That looks like a legitimate bulk mailing to a fairly well-maintained list, and not some random virus or brute-force spam attempt. Server resources are not being wasted on nonsense.