I have a message system on my website and a user was sending email through Message in .net (SmtpClient) to 1000 recipients. When mail is sent the user goes to a new aspx page that confirms that the email has been sent, but in this case it did not. I also update in sql database that the message has been sent, but in this case it was not updated. I know that at least some received the email.
There was an errormesage in Chrome console:
uncaught Sys.WebForms.PageRequestManagerServererrorexception: Sys.WebForms.PageRequestManagerServerErrorException: Unable to send to a recipient
I know there was at least one email that slipped through detection. It is something like "firstname.lastname@example.org".
Can someone explain why this happens and how I can prevent this from happening?
Does .net wait for a confirmation from the SmptClient before proceeding?
I am using .net and C#.