Create new mail with attachment via mailto protocol

I’m trying to create a new mail via the mailto protocol. The parameters are subject, attach (multi) and body. The files to attach may reside within folders having a space in its path name. The files exists definitively.

The mailto call is raised via the Java Desktop class ( Desktop.getDesktop().mail(new URI(sendtoText)) );

The mailto format looks like:

mailto:receiver-address@xyz.com?subject=someText&attach=/file1.ext&attach=/file2.ext&body=some text

The single parameters are url endcoded using the UTF-8 encoding.

Now the point:

It works the first time, when I newly started notes (intitially the start page is opened plus the new mail tab).

I’m closing the start page and the new mail and run the mailto command again - a new mail page is opened.

If I close it again and rerun the mailto I’m gettings the message “command can not be executed”.

What happens? May I find somewhere in the workspace a detailed log what the failed command is?

Is there a recommended format for the attach parameter within the mailto protocol?

Additionally: Some collegues reported that the attach parameters are not accepted at all, if the path contained a space. They are running notes 8.5.?

Thanks in advance for any kind of answer