Though back when I worked ISP operations our AV setup was quite nicely screwed over by a simple zip-that-unpacks-a-giant-file - since when it reached 2Gb the AV process would crash without cleaning up and eventually we ran out of unpacking space and couldn't process anything else either (but until then kept processing at about 75% normal speed because the bomb went back into queue for a bit after that).

Duct taped it by doing roughly 'rm /tmp/av_system//' in cron once a minute to keep things up while we tracked the offending email down and malleted it out of existence.

AV vendor intentionally not mentioned since >15 years later I'm sure their code is mostly different and mostly not maintained by the same people.