This was just an example of how careful you should be with follow up emails since it is not only fact that a subscriber unsubscribes. They are also associating your business with an annoying impression and this turned a semi-warm lead into a stone cold one.
The reason why I use this as two examples is that my impression of email marketing right now is that it gets even more aggressive and I don’t that is the right way to go. You need to find the right balance because, of course, you should try to chase abandoned clients.
My prediction for 2018 is that it becomes even more important to personalize your emails and segment your email list. By 2019 it is expected that there would 246 billion emails per day, so you should start to consider how you will stand out from the crowd. These statistics of 2018 will definitely shape my future email campaign.