At this time we believe the issue to be resolved.

We have released a fix and most tests should be able to send and receive emails now. There may continue to be some delay for a short time. We are monitoring.

Some workflows test features that involve sending and receiving emails. Recent changes to the emailer service that supports these tests are causing some emails to be rejected due to invalid email addresses, even when those addresses are actually valid.

We have identified the problematic code and are working on a hotfix.