As part of cloud infrastructure monitoring activities, Sitecore Cloud Operations team identified an event that we would like to bring to your attention.Users might experience an issue caused by the expiration of the sitecoremail.com domain that was used in the return path of the emails sent via EXM Delivery Cloud.Since the domain is no longer valid, in some cases, email providers bounce emails with such a return path.More details regarding the Update process for the config file is given in the following article

In case you have any follow up questions regarding the event, please do not hesitate to raise a support case on that matter from the home page of Sitecore Support & Self-Service Portal.