[Zope] How to skip validation when uploading

I would like to upload some regular html files using ftp port 8021. However if the files are not valid html it simply won't upload them, and it put an error message in the log (not containing the line number of the error). If I make a new document in zope (plone), and copy and paste the same code in it, zope is much more liberal about the code. Is it possible to remove the check when uploading ?