C#、.NET版邮件（群）发系统

private void btnOK_Click(object sender, EventArgs e)
{
NewInforLine = txtSMTP.Text + " " + txtSenderEmail.Text + " " + txtSenderPwd.Text;
Regex regex = new Regex(@"^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$"); //验证Email格式
if (regex.IsMatch(txtSenderEmail.Text.Trim()) && txtSenderPwd.Text.Trim() != "")
{
if (arg) //修改发件人
{
string[] content;
string[] content1;
try
{
content = File.ReadAllLines(PathBase + inforpath, Encoding.Default);
content1 = new string[content.Length];
for (int i = 0; i < content.Length; i++)
{
if (content[i] != OldInforLine)
{
content1[i] = content[i];
continue;
}
content1[i] = NewInforLine;
}

FileStream stream2 = File.Open(inforpath, FileMode.OpenOrCreate, FileAccess.Write);
stream2.Seek(0, SeekOrigin.Begin);
stream2.SetLength(0); //清空txt文件
stream2.Close();
File.WriteAllLines(PathBase + inforpath, content1);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
else //添加发件人
{
using (FileStream stream = new FileStream(inforpath, FileMode.Append, FileAccess.Write))
{
using (StreamWriter write = new StreamWriter(stream, Encoding.Default))
{
string stremail = txtSMTP.Text + " " + txtSenderEmail.Text + " " + txtSenderPwd.Text;
write.WriteLine(stremail);
}
}
}
ClearContent();
this.DialogResult = System.Windows.Forms.DialogResult.OK;
}
else
{
MessageBox.Show("邮箱格式不正确", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
this.DialogResult = System.Windows.Forms.DialogResult.None;
}
}