.Net System.Mail.Message adding multiple “To” addresses

Question

EDIT: This question is pointless, except as an exercise in red herrings. The issue turned out to be a combination of my idiocy (NO ONE was being emailed as the hos

Answer 1

You can do this either with multiple System.Net.Mail.MailAddress objects or you can provide a single string containing all of the addresses separated by commas

Answer 2

You could try putting the e-mails into a comma-delimited string ("person1@domain.com, person2@domain.com"):

C#:

ArrayList arEmails = new ArrayList();
arEmails.Add("person1@domain.com");
arEmails.Add("person2@domain.com");
           
string strEmails = string.Join(", ", arEmails);

VB.NET if you're interested:

Dim arEmails As New ArrayList
arEmails.Add("person1@domain.com")
arEmails.Add("person2@domain.com")

Dim strEmails As String = String.Join(", ", arEmails)

Answer 3

I wasn't able to replicate your bug:

var message = new MailMessage();

message.To.Add("user@example.com");
message.To.Add("user2@example.com");

message.From = new MailAddress("test@example.com");
message.Subject = "Test";
message.Body = "Test";

var client = new SmtpClient("localhost", 25);
client.Send(message);

Dumping the contents of the To: MailAddressCollection:

MailAddressCollection (2 items)
DisplayName User Host Address

user example.com user@example.com
user2 example.com user2@example.com

And the resulting e-mail as caught by smtp4dev:

Received: from mycomputername (mycomputername [127.0.0.1])
     by localhost (Eric Daugherty's C# Email Server)
     3/8/2010 12:50:28 PM
MIME-Version: 1.0
From: test@example.com
To: user@example.com, user2@example.com
Date: 8 Mar 2010 12:50:28 -0800
Subject: Test
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: quoted-printable

Test

Are you sure there's not some other issue going on with your code or SMTP server?

Answer 4

private string FormatMultipleEmailAddresses(string emailAddresses)
    {
      var delimiters = new[] { ',', ';' };

      var addresses = emailAddresses.Split(delimiters, StringSplitOptions.RemoveEmptyEntries);

      return string.Join(",", addresses);
    }

Now you can use it like

var mailMessage = new MailMessage();
mailMessage.To.Add(FormatMultipleEmailAddresses("test@gmail.com;john@rediff.com,prashant@mail.com"));

Answer 5

Thanks for spotting this I was about to add strings thinking the same as you that they'd get added to end of collection. It appears the params are:

msg.to.Add(<MailAddress>) adds MailAddress to the end of the collection
msg.to.Add(<string>) add a list of emails to the collection

Slightly different actions depending on param type, I think this is pretty bad form i'd have prefered split methods AddStringList of something.

Answer 6

Add multiple System.MailAdress object to get what you want.