public Task<Pop3CommandReply> HandleUidl()
{
var builder = new StringBuilder();
builder.AppendFormat("\r\n");
for (int i = 0; i < _messages.Count; i++)
{
var message = _messages[i];
if (message.Deleted)
continue;
builder.AppendFormat("{0} {1}\r\n", i + 1, message.Uid);
}
builder.Append(".");
return Task.Run(() => new Pop3CommandReply(true, builder.ToString()));
}