CODEWITHSUNDEEP
c#.net
Aron
Aron

Reputation: 107

how to send email in C# even when one of the recipient is invalid?

I am trying to send email to multiple recipients and it works fine when all the recipients have valid email address.

But when one of the recipients have invalid email address, email is not sent even to other recipients whose email address is valid and I am getting an exception:

The server rejected one or more recipient addresses. The server response was: 550 #5.1.0 Address rejected.

Is there any way I can send the email to other valid recipients even if one of the email address is invalid?

public static void sendMails(string ptxtSubject, string ptxtBody)
{
    string txtTo = "[email protected],[email protected],[email protected]";
    string txtFrom = "[email protected]";
    string txtSubject = ptxtSubject;
    string txtBody = ptxtBody;

    MailMessage mail = new MailMessage();
    mail.To = txtTo;
    mail.From = txtFrom;
    mail.Subject = txtSubject;
    mail.Body = txtBody;

    try
    {
        SmtpMail.SmtpServer ="smtp.aaa.com";
        SmtpMail.Send(mail);
    }
    catch (Exception ex)
    {
       //log the exception
       throw;  
    }
}

I can send separate mail to each of them but users(recipients) will not know who else is in the email distribution list. My requirement is everyone should be able to know who else is receiving the email.

Outlook sends the email to all the valid users and notifies us back of invalid users. Is there anyway we can do the same using C#?

Upvotes: 3

Views: 3403

Answers (2)

Tim M.
Tim M.

Reputation: 54377

Unless all the recipients definitely know each other (and they don't mind other people knowing they are receiving email from you), you should be sending separate emails anyway.

This would also take care of your problem, i.e. if one send operation fails, it won't disrupt the others. Note that in your case, it appears that the initial relay is failing because the addresses are from the same host as the SMTP server.

Once an email is routed to multiple hosts, the success/failure is no longer interdependent. For example, a gmail.com server probably doesn't know/care that a yahoo.com server rejected a recipient.

If performance is a concern, you can send the messages asynchronously to get achieve better throughput. Note that you can still handle exceptions when sending asynchronously.

As always, if you are sending any quantity of email, it's probably advisable to use a 3rd party service.

Upvotes: 3

Jonathan Wood
Jonathan Wood

Reputation: 67223

I really don't see any way to accomplish this. Sending an email with SmtpMail.Send() is pretty much an atomic function and you need correct data for it to work without an exception.

The only option I see here is to send separate emails to each recipient.

Upvotes: 1

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