I tried to stop a marketing email that was Live. It took a long time and then I got an error message: "The specified domain does not exist or cannot be contacted". The error appears to be from a plugin:

Unexpected exception from plug-in (Execute): Microsoft.Dynamics.Crm.MarketingPlugins.Plugins.Email.PublishEmailEntityPlugin: System.TimeoutException: Couldn’t complete execution of the Microsoft.Dynamics.Crm.MarketingPlugins.Plugins.Email.PublishEmailEntityPlugin plug-in within the 2-minute limit. An unexpected error occurred from ISV code.