For testing email advisable to use a special kind of testing - Split testing (or A/B testing). UniSender is a service that allows you to automate the A/B test and reduce the time of result analysis to a minimum. UniSender has the option to choose a free plan for 1 year. You can send up 1500 emails per month with no more than 100 subscribers.
Speed and reliability testing (load / stress / performance testing). This test helps to check a behaviour of websites (or its parts) at the same time with an influx of a lot of users. Poor performance (speed) - this is the main issue of many Internet projects. You can build really cool useful site, but low performance could decreased all your achievements.
On many occasions the most common fixing suggestions are to clear your cache and cookies if you want your browser to work effectively and without delays. In most of the cases clearing out your cache and cookies is not only a crucial problem-solving step, and it may really sound like you just need “to restart”, but it can be a great solution altogether.