验证电子邮件的主题行

Question

Some characters are invalid in an email subject and will result in failure, for example carriage return. I accept subject line as an input.

Is there a definitive description of what makes a valid email Subject? I've looked in the what I think is the correct RFC spec and can't find any.

Are there any .Net libraries that will validate/sanitise an email subject line? Particularly is there anything in the core libraries or in MailKit ?

Answer 1

Just make sure there are no newline or carriage returns. That is what System.Net.Mail does.

//This is from the MailBnfHelper class of the System.Net.Mime namespace.
internal static bool HasCROrLF(string data)
    {
      for (int index = 0; index < data.Length; ++index)
      {
        if (data[index] == '\r' || data[index] == '\n')
          return true;
      }
      return false;
    }