在邮件标题中发现无效字符：';' 在 C# 中

Question

I'm using System.Net.Mail to send email in my application but I get an exception and I can't figure out what/where the problem is and how to fix it.

The error says I have some invalid char:

An invalid character was found in the mail header: ';'.

I tried google without success.

The string with email address is:

john@mydomain.org; beth@mydomain.org; alfred@mydomain.org; barbie@mydomain.org; 

Here is my email sending code:

    SmtpClient smtpClient = new SmtpClient("smtp.........");
    System.Net.Mail.MailMessage mailMessagePlainText = new System.Net.Mail.MailMessage();

    mailMessagePlainText.IsBodyHtml = true;
    mailMessagePlainText.From = new MailAddress("vincent@mydomain.org", "admin");

    mailMessagePlainText.Subject = "test";
    mailMessagePlainText.Body = "test";

    mailMessagePlainText.To.Add(new MailAddress(List1.ToString(), ""));
    mailMessagePlainText.Bcc.Add(new MailAddress("vincent@mydomain.org", ""));

    try
    {
        smtpClient.Send(mailMessagePlainText);
    }
    catch (Exception ex)
    {
        throw (ex);
    }

Answer 1

foreach (var address in List1.split(';')) {
    mailMessagePlainText.To.Add(new MailAddress(address.Trim(), ""));
}

Because according to your string here above, each address in this loop above would produce following:

"john@mydomain.org"
" beth@mydomain.org"
" alfred@mydomain.org"
" barbie@mydomain.org"

So by adding .Trim() to address would make your code work.

Answer 2

A MailAddressCollection (like your mailMessagePlainText.To ) has an Add method that accepts a string containing a list of mail addresses, separated by a comma .

So to use that, you will need to change the ; into a , and possibly remove the extra spaces.

Answer 3

It looks like you're adding the addresses as a single MailAddress, where you need to add them 1 at a time. I don't know what other overloads are available, but the following will probably work.

I split the string by ; and add each address separately.

replace

mailMessagePlainText.To.Add(new MailAddress(List1.ToString(), ""));

with

foreach (var address in List1.split(';')) {
    mailMessagePlainText.To.Add(new MailAddress(address , ""));
}