Honeycomb engages event throttling as a last resort, when an account has exceeded its events per month (EPM) limit for two months in a row.
Before to reaching this state, Honeycomb does automatically email team owners when their usage seems to be trending toward overage, and again when usage initially exceeds the EPM limit.
You can read more about EPM overages in Honeycomb's usage documentation. (Note: Enterprise customers are exempt from throttling.)
If you find your team in a throttled state, you have options! You may wish to consider a different configuration, employing sampling, or upgrading your Honeycomb plan. Please do reach out to us in Support if you have any questions; we like to help people avoid this state!