The intermittent email delays spotted on June 12, 2020, were caused by a custom regular expression of a message rule. The team identified the rule and confirmed that when it was used to evaluate an incoming email, it would take a very long time and use excessive computing resources.

The offending rule has been modified to prevent runaway resource utilization, and inbound email performance has been operating at normal levels.

Additional logging and notification have been put in place to alert Mailprotector of custom regular expressions that could cause resource problems. Long-term solutions are being explored to continue providing the flexibility of custom regular expressions without the risks of problem rules causing system-wide performance implications.