To send a PDF page via e-mail, you can render the page to a bitmap using the below code, save and send. 

Document doc = new Document();
if( doc.Open(m_path, null) == 0 ) {
    int iw = thumb_width;
    int ih = thumb_height;
    Page page = doc.GetPage0();

    Bitmap bmp = Bitmap.createBitmap( iw, ih, Bitmap.Config.ARGB_8888 );
    bmp.eraseColor(0);

    float w = doc.GetPageWidth(0);
    float h = doc.GetPageHeight(0);
    float ratiox = iw/w;
    float ratioy = ih/h;
    if( ratiox > ratioy ) ratiox = ratioy;
    Matrix mat = new Matrix( ratiox, -ratiox, (iw - w * ratiox)/2, (ih + h * ratiox)/2 );
    page.RenderToBmp(bmp, mat);
    mat.Destroy();

    try {
       FileOutputStream fos = new FileOutputStream(pictureFile); //pictureFile the path of the bitmap to pass to send intent
       bmp.compress(Bitmap.CompressFormat.PNG, 90, fos);
       fos.close();
    } catch (Exception e) {
       e.getMessage();
    }
    bmp.recycle();
    page.Close();
    doc.Close(); 
//send pictureFile by mail
} 

Or if you have a premium license, you can extract the PDF page(s) into a separate PDF, save and send. 

    Document document = new Document();
    if(document.Open(path, password) == 0) {
            Document new_doc = new Document();
            new_doc.Create( destFile ); //destFile the path of the destination file to pass to send intent
            new_doc.Open(destFile, null);
            new_doc.SetCache( file_cache );

            Document.ImportContext ctx = new_doc.ImportStart(document);
            boolean result = false;
            for (int i = 0 ; i < mPages.length ; i++) //mPages array containing the page numbers to send
                result = new_doc.ImportPage(ctx, mPages[i].getPageNum() - 1, i);
            ctx.Destroy();

            new_doc.Save();
            new_doc.Close();

            document.Close();
            if(resul)
                //send destFile by mail
    }