Internal Server Error on Send tokenized e-mail trigger

Could be related to: #357131: Internal Server Error on adding the comment

It's because 'Recipient:' is not required field as in normal 'Send email...' action.
If you leave it empty, it generates Internal Server Error.

This could be done by hook_validate as it's done already in system module.

Yes, it solved my issue.
When first I saw this error, I used Workflow.
I've created Workflow, with state 'new'. Added permission to create this state for Anonymous, and then assigned action when specified content is created and when it have a 'new' state, then send tokenized e-mail.
So I started to diagnose the problem, so I've disabled Workflow module and assigned action directly on Node creation, so I still had a problem on submitting this form.
So I edited tokenized e-mail action, and I thought before that if I leave Recipient empty it will be set to my site_mail. But when I set Recipient to some non-empty e-mail then it worked - no error anymore.
I don't know why you can't reproduce it. Try to create two tokenized e-mail actions, I had two of them, but only one was assigned.
Internal Server Error could depends on the server configuration, maybe some other connection or some conflicts between some modules.

Basically the problem was Internal Server Error on submitting content when "Send tokenized e-mail..." action was assigned, and it was solved when I've put some e-mail in Recipient field.

So the question is, if you allow it to be empty, so to what address it will send the e-mail?

I'll try to reproduce it on the other website and somebody will have similar problem.