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Hello, 
I have a message system on my website and a user was sending email through Message in .net (SmtpClient) to 1000 recipients. &nbsp;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. &nbsp;It is something like &quot;t.d.johnjohnsson@someaddress.com&quot;. 
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#. 
 
Greetings
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Hello,
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 "t.d.johnjohnsson@someaddress.com".
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#.

Greetings

.net mail error - unable to send to a recipient

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

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The successor to Active Server Pages, ASP.NET websites utilize the .NET framework to produce dynamic, data and content-driven web applications and services. ASP.NET code can be written using any .NET supported language. As of 2009, ASP.NET can also apply the Model-View-Controller (MVC) pattern to web applications

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