The Salesforce Technology team has discovered a service disruption at 9:05 PM UTC in Marketing Cloud that may affect a subset email sending from your Pardot instance. This service disruption has now been resolved as of 10:57 PM UTC.
Please refer to the Trust message at https://status.salesforce.com/incidents/6487
for further information.
We sincerely regret any inconvenience you have experienced as a result of this incident.