به اینصورت اصلاح کن:
DataTable dt = new DataTable();
dt.Columns.Add("Email");
dt.Rows.Add("1@yahoo.com");
dt.Rows.Add("2@yahoo.com");
dt.Rows.Add("3@yahoo.com");
dt.Rows.Add("4@yahoo.com");
dt.Rows.Add("5@yahoo.com");
dt.Rows.Add("6@yahoo.com");
dt.Rows.Add("7@yahoo.com");
dt.Rows.Add("8@yahoo.com");
MailMessage msg = new MailMessage();
int count = 3;
//try
{
label2.Text = dt.Rows.Count.ToString();
for (int offset = 0; offset < dt.Rows.Count; offset+=count)
{
msg.To.Clear();
string tempStr = string.Empty;
int newIndex = 0;
for (int indexer = 0; indexer < count; indexer++)
{
newIndex = offset + indexer;
if (newIndex < dt.Rows.Count)
{
string strEmail = dt.Rows[newIndex]["Email"].ToString();
tempStr += strEmail + "\t";
msg.To.Add(strEmail);
}
}
listBox2.Items.Add(tempStr);
//client.Send(msg);
}
}