Can I insert a subscribe form via shortcode?
Sure. Postmatic comes with a shortcode which will allow you to display the subscribe form within a post, page, or otherwise. In order to display the Postmatic subscribe form use the following:
[postmatic_subscribe_widget]
By default the shortcode will display the subscribe form and ask for both name and email address. If you would prefer to not collect names set collect_name="false" like this:
[postmatic_subscribe_widget collect_name="1"]
You can also display a title with the form:
[postmatic_subscribe_widget title="Subscribe Now!"]