c# - How to loop through all MailItems of certain Outlook subfolders -

i'm working on outlook 2007 add-in. found code loop through folders have not been able figure out how loop inside given folder examine mailitem objects (ultimately, want save emails elsewhere , modify .subject property).

here have far:

 private void btnfolderwalk_click(object sender, eventargs e)     {         // retrieve name of top-level folder (inbox) ,          // purposes of demonstration.         outlook.folder inbox = application.session.getdefaultfolder(outlook.oldefaultfolders.olfolderinbox)           outlook.folder;        // cast mapi folder returned outlook folder         // retrieve reference top-level folder.         if (inbox != null)         {             outlook.folder parent = inbox.parent outlook.folder;   // mailbox             if (parent != null)             {                 recursethroughfolders(parent, 0);             }         }     }     private void recursethroughfolders(outlook.folder therootfolder, int depth)     {         if (therootfolder.defaultitemtype != outlook.olitemtype.olmailitem)         {             return;         }         lbmail.items.add(therootfolder.folderpath);         foreach (object item in therootfolder.items)         {             if (item.gettype() == typeof(outlook.mailitem))             {                 outlook.mailitem mi = (outlook.mailitem)item;                 lbmail.items.add(mi.subject);             //-------------------------------------------------------------------------             //  mi.subject folder name it's full path.              //  how "open it" emails?             //  need loop here modify .subject of mailitem(s) in subfolders             //-------------------------------------------------------------------------             }         }         foreach (outlook.folder folder in therootfolder.folders)         {             recursethroughfolders(folder, depth + 1);         }     } 

i'm using listbox @ stage of working things out , output looks below. want "process" email messages of "projectnnnnnn" folders.

\\personal folders \\personal folders\deleted items \\personal folders\inbox \\personal folders\inbox\mysubfolder \\personal folders\inbox\mysubfolder\project456212 \\personal folders\inbox\mysubfolder\project318188 \\personal folders\inbox\outbox \\personal folders\inbox\sentitems 

edit:

i fixed slight change in loop above (i.e. removing check current item mailitem):

foreach (object item in therootfolder.items)     {             outlook.mailitem mi = (outlook.mailitem)item;             string modifiedsubject = "modifed subject: " + mi.subject;             lbmail.items.add(modifiedsubject);             mi.subject = modifiedsubject;             mi.save();      //          insert call webservice here upload modified mailitem new data store     } 

while above code may work come across unhandled invalidcastexception not items in root folder mail items (e.g. meeting requests).
following code worked me:

foreach (object item in items) {     if (item outlook.mailitem)     {         ///the rest of code     } }