确定System.Net.Mail.SmtpClient.Send结果

我试图用枚举来总结System.Net.Mail.SmtpClient.Send的结果。这是让我知道我是否应该重试发送电子邮件，并希望防止重复的电子邮件被发送。

public enum MailSendStatus {
    None,
    Sent,
    ErrorCannotSend,
    TryAgain,
    SentMaybe
}

我已经捕获了Send的所有异常，并从http://msdn.microsoft.com/en-us/library/system.net.mail.smtpstatuscode(v=vs.80).aspx中分离出SmtpException.StatusCode s。故障看起来正确吗?还是有更好的方法?

try {
    smtp.Send(msg);
} catch (ArgumentNullException e) {
    return MailSendStatus.ErrorCannotSend;
} catch (ObjectDisposedException e) {
    return MailSendStatus.ErrorCannotSend;
} catch (InvalidOperationException e) {
    return MailSendStatus.ErrorCannotSend;
} catch (SmtpFailedRecipientsException e) {
    return MailSendStatus.ErrorCannotSend;
} catch (SmtpException e) {
    switch(e.StatusCode) {
        case SmtpStatusCode.BadCommandSequence:
        case SmtpStatusCode.MailboxNameNotAllowed:
        case SmtpStatusCode.HelpMessage:
        case SmtpStatusCode.SyntaxError:
        case SmtpStatusCode.SystemStatus:
            return MailSendStatus.ErrorCannotSend;
        case SmtpStatusCode.CannotVerifyUserWillAttemptDelivery:
        case SmtpStatusCode.UserNotLocalWillForward:
            return MailSendStatus.SentMaybe;
        case SmtpStatusCode.ClientNotPermitted:
        case SmtpStatusCode.CommandNotImplemented:
        case SmtpStatusCode.CommandParameterNotImplemented:
        case SmtpStatusCode.CommandUnrecognized:
        case SmtpStatusCode.ExceededStorageAllocation:
        case SmtpStatusCode.GeneralFailure:
        case SmtpStatusCode.InsufficientStorage:
        case SmtpStatusCode.LocalErrorInProcessing:
        case SmtpStatusCode.MailboxBusy:
        case SmtpStatusCode.MailboxUnavailable:
        case SmtpStatusCode.MustIssueStartTlsFirst:
        case SmtpStatusCode.ServiceClosingTransmissionChannel:
        case SmtpStatusCode.ServiceNotAvailable:
        case SmtpStatusCode.ServiceReady:
        case SmtpStatusCode.StartMailInput:
        case SmtpStatusCode.TransactionFailed:
        case SmtpStatusCode.UserNotLocalTryAlternatePath:
            return MailSendStatus.TryAgain;
        case SmtpStatusCode.Ok:
            break;
    }
} catch (Exception e) { 
    return MailSendStatus.SentMaybe;
}
return MailSendStatus.Sent;

catch (ArgumentNullException e) {    return MailSendStatus.ErrorCannotSend;} catch 
(ObjectDisposedException e) {    return MailSendStatus.ErrorCannotSend;} catch 
(InvalidOperationException e) {    return MailSendStatus.ErrorCannotSend;