title: PHP MailSo library and attachments
body: <p>I'm trying to use <a href="https://github.com/detochko/MailSo" rel="nofollow noreferrer">MailSo</a> library to create MIME message. I have got to the point where next step is to process attachments. Everything is fine when attachments are binary files but when I try to to add plain text attachment as follow</p>
  
  <pre><code>$rResource = "Some plain text goes here";
  $sFileName = 'text.txt';
  $iFileSize = \strlen("Some plain text goes here");
  $bIsInline = false;
  $bIsLinked = false;
  $sCID = $metadataCID;
  $aCustomContentTypeParams = array(\MailSo\Base\Enumerations\Encoding::QUOTED_PRINTABLE_LOWER);
  
  $oMessage-&gt;Attachments()-&gt;Add(
      \MailSo\Mime\Attachment::NewInstance(
          $rResource,
          $sFileName,
          $iFileSize,
          $bIsInline,
          $bIsLinked,
          $sCID,
          $aCustomContentTypeParams
      )
  );
  </code></pre>
  
  <p>I expect to see that attachment as</p>
  
  <pre><code>Content-Type: text/plain; charset="utf-8" 
  Content-Transfer-Encoding: quoted-printable 
  Content-Disposition: attachment; filename=text.txt 
  </code></pre>
  
  <p>but it always forcing to base64 neither adding charset to content-type part as</p>
  
  <pre><code>Content-Type: text/plain; name="text.txt" 
  Content-Disposition: attachment; filename="text.txt" 
  Content-Transfer-Encoding: base64 
  </code></pre>
  
  <p>Any tips on that?</p>