Hey there,

I am really sorry for the delay of this reply as it is a weekend for us here.

1.
is it possible to have a post preview link, that can be send to a partner and he doesn't have to login to access it?

Unfortunately that was no setting for this, but you can modify on this core file -> JoomlaFolder/components/com_easyblog/views/entry/view.html.php

Comment out these few line of code.

		// Perform validation checks to see if post is valid

		// $exception = $post->checkView();



		// if ($exception instanceof EasyBlogException) {

		// 	return JError::raiseError(400, $exception->getMessage());

		// }

You can refer on my attached screenshot below.

2.
i have actived the secure cronjob-url, but don't find how to add the key to the url. could you please give me a hint

After you enter your secure key into that field, you have to click save. (You can refer on my screenshot below)
After you click save, it will populate the cron URL with the secure key, so this URL you have to configure from your server under cronjob setup area.

You can refer our documentation here how to setup cronjob on your server.
https://stackideas.com/docs/easyblog/administrators/cronjobs

many thanks, for your feedback.

for the cronjob link, as the url wasn't visible with saving, i thought it was an error.

and thanks for the workaround, it works perfect like this

You are most welcome, glad that your issue is resolved now