private static string EncodeHeaderValue(string value)
{
StringBuilder sb = new StringBuilder();
if (StringHandler.IsAscii(value))
{
return(value);
}
if (StringHandler.IsAnsi(value))
{
Encoding enc = Encoding.GetEncoding(1252);
sb.Append("=?");
sb.Append(enc.BodyName);
sb.Append("?Q?");
sb.Append(StringHandler.EncodeToQuotedPrintable(value, enc, true));
sb.Append("?=");
}
else
{
sb.Append("=?utf-8?B?");
sb.Append(Convert.ToBase64String(Encoding.UTF8.GetBytes(value)));
sb.Append("?=");
}
return(sb.ToString());
}
private static void AppendMessage(StringBuilder sb, string message, string format, Encoding encoding)
{
if (message == null)
{
message = string.Empty;
}
sb.Append("Content-Type: text/");
sb.Append(format);
if (StringHandler.IsAscii(message))
{
sb.Append("\r\n");
sb.Append("Content-Transfer-Encoding: 7Bit\r\n");
sb.Append("\r\n");
sb.Append(message);
}
else
{
if ((encoding == null && !StringHandler.IsAnsi(message)) || (encoding != null && encoding.Equals(Encoding.UTF8)))
{
sb.Append("; charset=utf-8\r\n");
sb.Append("Content-Transfer-Encoding: base64\r\n");
sb.Append("\r\n");
string base64String = Convert.ToBase64String(Encoding.UTF8.GetBytes(message));
ChunkString(sb, base64String, 73);
}
else
{
if (encoding == null)
{
encoding = Encoding.GetEncoding(1252);
}
sb.Append("; charset=");
sb.Append(encoding.BodyName);
sb.Append("\r\n");
sb.Append("Content-Transfer-Encoding: quoted-printable\r\n");
sb.Append("\r\n");
sb.Append(StringHandler.EncodeToQuotedPrintable(message, encoding));
}
}
if (!message.EndsWith("\r\n"))
{
sb.Append("\r\n");
}
sb.Append("\r\n");
}