I can't imaging that CEON URI mapping would cause a problem with your emails even if you did make a mistake editing the files. All (as far as I know) the edits in the core files are just to include classes and files for CEON so it shouldn't do anything to the emails. If you are still convinced it's something you did when editing files why not just look through all the files you edited and winmerge them with original zen1.5 files and see if you've accidentally deleted something