This incident has been resolved.
May 12, 00:15 UTC
Sendgrid report that "all mail has since been dequeued and is being processed once again without delay". We confirmed this on our end so are marking this as resolved.
May 12, 00:12 UTC
Our email server provider, Sendgrid, is investigating this issue and we will provide updates as well have them.
May 11, 23:28 UTC
We are investigating reports of email delivery delays. We believe they are caused by processing delays from our email server provider. We will update this status as soon as possible.
May 11, 23:12 UTC