1. Normally how many message emails your website receive per minute?
2. was that happening for single message or multiple messages?
3. How much was the size of that message? any difference in that message with other messages?
4. It may possible that in 1 minute message process is not completed. Can you set as 5 minutes instead of 1 minute cron so that multiple imap connection is not open?
And is there a function to pause the FEP_POP_3 cronjob when there’s a fatal error? Because this can happen again in the future and when it’s at night, the cronjob will run the whole night without me noticing it.
I do not know how this error even possible. Did you declare this function inside another function?
You can wrap this function inside function_exists call so that this error never happen.
This error also can be issue for email not deleted, But as i cannot see full code, i cannot be sure. But any fatal error can create that issue. Please wrap that function inside function_exists and see if working.