@donCalpe
That's because those feeds produce pages that look like this
Code:
<!-- Bottom build 2.30 -->
<!-- Setup build 3.03 -->
<!-- Kontingent hashmap build 2.52 -->
<!-- Regroup hashmap build 2.45 -->
<!-- Level2 hashmap build 1.18 -->
<!-- Sitestat build 2.39 -->
<!-- End Sitestat4 code -->
<!-- Ohters build 2.21 -->
<!-- FragebogenOEWA -->
<!-- /FragebogenOEWA -->
<!-- Begin Sitestat4 Technical code -->
<!-- End Sitestat4 Technical code -->
java.lang.NullPointerException
at java.util.regex.Matcher.getTextLength(Matcher.java:1140)
at java.util.regex.Matcher.reset(Matcher.java:291)
at java.util.regex.Matcher.<init>(Matcher.java:211)
at java.util.regex.Pattern.matcher(Pattern.java:888)
at org.apache.jsp.portal.services.article.print_jsp._jspService(print_jsp.java:125)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:334)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
at org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcessor.java:263)
at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
at org.apache.struts.tiles.TilesRequestProcessor.processForwardConfig(TilesRequestProcessor.java:318)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at at.beit.portal.tools.urlredirect.URLRedirectFilter.doFilter(URLRedirectFilter.java:120)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:425)
at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:452)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1285)
at java.lang.Thread.run(Thread.java:619)
</init>
Try setting your output format to epub and then convert the epub to mobi, that will strip these kinds of pages.