The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Authentication required
Using the default Email Action item for Workflow action in Sitecore 7.2 takes the following parameters: To (To Email) From (From Email) Subject Message (Body) Mail Server (Host) Type (default: Sitecore.Workflows.Simple.EmailAction, Sitecore.Kernel) If the mail server uses authentication, which most email hosts do, you get the following error: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Authentication required Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Net.Mail.SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Authentication required Source Error: An unhandled exception was generated during the execution of the current ...