Read the documentation. I'm sure it'll tell you what happens if it fails to upload the file. Perhaps it returns false if that happens?

Once you know what happens after failure, you should be able to cater for that.

I would presume that your $ftp->put($new) or die "$server: cannot put $new: " . $ftp->message; would be sufficient myself...

If you're seeing cases where $ftp->put($new) is not returning false and if that's what the documentation says it should and the file is not being successfully transferred then that's a different matter, and one I can't help you with.

If you are seeing cases like that then you should try to identify under what circumstances that's happening. If you can identify the circumstances, and repeat the problem, but not fix it, then that would make an excellent SOPW question.

All the best,

jarich