If one of the users is having email account of invalid domain, then Reports/Alerts is not sent to other users also having valid email accounts. Why?

If one of the users is having email account of invalid domain, then Reports/Alerts is not sent to other users also having valid email accounts. Why?

ARC does not validate the domain names and hence the reports fail if one of the users subscribed in an Alert/Report contains an email account from an invalid domain. Please contact your network team and get all the domains enabled (whichever the business users use to schedule reports/alerts) in the SMTP server