remote name could be solved : "smtp.gmail.com"

Question

i have web mail application with multiple attachment sending facility. i have used port 587 to send mail from gmail & have given my id & password. i have file upload option also. i have used system.net.mail namespace also. earlier i could send mail but nw it says
"

Server Error in '/' Application.

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The remote name could not be resolved: 'smtp.gmail.com'

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.WebException: The remote name could not be resolved: 'smtp.gmail.com'

Source Error:

ine 46:             client.EnableSsl = true;
Line 47: 
Line 48:             client.Send(mail);

Please help in this regard.

Thanks in advance,

Avinash