Hello @lucian.cristian -
I’m not aware of a KNIME node that will do this neatly - although I am happy to be shown otherwise! It may be possible to do it using the External Tool node. Here I’m thinking you could call another program, like 7zip, in which you would compress your files, encrypt them, and add a password using a single command. (Example: How to encrypt txt files with AES256 via Windows 7z command line? - Super User)
Here’s an example workflow I modified to use the External Tool node to perform some image processing using a third-party program. I had to wrap the External Tool inside some Try/Catch nodes for it to work properly. You can see how this was done inside the “Call ImageMagick” metanode.
Maybe this will help? I know it’s not straightforward, but if you’ve already got a working loop built to send emails, maybe this won’t be too much trouble to implement.