Find out all the Message server entries.

CMsvEntry *inbox=iSession->GetEntryL(KMsvGlobalInBoxIndexEntryId);
CMsvEntrySelection *children=inbox->ChildrenWithMtmL(KUidMsgTypeSMS); // KUidMsgTypeMultimedia
for(TInt i=0;i<children->Count();i++)
    {
    CMsvEntry *child=inbox->ChildEntryL((*children)[i]);
    const TMsvEntry &entry=child->Entry();
    ...
    }