What are some alternatives?
When comparing WPMU DEV and Jackmail, you can also consider the following products
Gravity Forms - Gravity Forms is one of the best and easiest contact form plugins to create modern forms for websites powered by widely-used WordPress.
Yoast Plugins - Yoast offers plugins to improve SEO and optimize web sites and blogs.
Pareto Security - Pareto Security is a Wordpress Security plugin
The SEO Framework - Easy SEO for beginners, an awesome API for experts. WordPress SEO for everyone.
MAMP - MAMP is the abbreviation for Macintosh, Apache, MySQL, and PHP. It is a reliable application with its four components that allows you to access the local PHP server as well as the database server (SQL).
Wordfence - Comprehensive security plugin for WordPress.