Add product attribute columns to Woocommerce backend grid

If you have to extend the backend product grid of Woocommerce by an custom attribute , you have to follow the steps below to add product attribute columns to Woocommerce backend grid: Register and sort  the new columns via a filter hook (‘manage_edit-product_columns’):

Add an action hook to fill in the respective value of each row […]

wordpress cron: using wp_mail function

Today I had to solve the problem, that my wordpress cron throws an exception like this when sending an email via wp_mail function inside a cron scheduled event function.

The wordpress cron was registered like that:

And the wordpress cron mechanism was triggered via Linux crontab:

Problem with wp_mail in wordpress cron […]