Since a few weeks we are receiving some email apparently send via our contact form but wihtout any data, we receiving only the name of the variables used by the toolset contact form. This error happen several times a day, but not always a few emails are correct.
Hello. Thank you for contacting the Toolset support.
I see you are using the custom place holders and there is no other users reported such issue and again its really hard to say whats going on as you acknowledged that it works sometimes and sometimes not.
You will have to keep eye on the site and keep track of actions and check what action made email not working as expected.