i am sending mail on our company id successfully send but if i am sending email any gmail and yahoo id i get bello error: in asp.net 1.1 Server Error in '/WebApplication1' Application. The message could not be sent to the SMTP server. The transport error code was 0x80040217. The server response was not available 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.Runtime.InteropServices.COMException: The message could not be sent to the SMTP server. The transport error code was 0x80040217. The server response was not available Source Error: