We had a problem today at a school where the out traffic was spiking regularly and internet connections were terrible. After lots of looking a packet capture showed that one IP was hitting port 25 (SMTP) over and over again. Didn’t make much sense so we tracked down the machine and found that there was a large email, trying to send, failing, and repeating that was the cause of the problem. This video replicated the problem at the board office trying to send a 120Mb file.
