Zombies of the email kind can be costly. They creep up in your mailing list, feed not so much on brains than on budgets by blowing up the number of subscribers. This ends up costing you and your organization money. Real money. For nothing. There's many ways to get rid of email zombies. One of them, which just hit Product Hunt, is using Kirim Email. According to the provider, it's easier and cheaper than hiring a sniper to shoot those monsters in the head.
Marketing automation tools are great, but they can be overwhelming and costly. They eat up your time and your budget, to the point where they negate much of the advantages of maintaining a mailing list to start with. So what if your mailing list is tight and you don't really need all the bells and whistles of an advanced automation tool? What if you could do much of what those tools can do using only your trusted Gmail client? That's where YAMN (Yet Another Mail Merge). It provides all the necessary functionality of more advanced tools, without the hassle.
So killing Zombies that roam your list and managing the surviving subscribers is great, but you still need to optimize your email content. That's where testing comes in. Here's a great -- albeit short -- introduction to efficient email content testing, with awesome examples.