I'm impressed by the 2025 version of Acumbamail. I saw previous versions of this product, but never pulled the trigger to buy it until now. Part of the reason is due to the fact that I almost impulsively buy email marketing solutions. I believe it was a few years ago that I first saw this product. At that time I thought, "Here's yet another email marketing solution that I'll probably buy and barely use." Fastforward until today and things have changed. Email deliverability tools and automation workflows make life so much easier. Even if you don't use them right now, the fact that they're there allows you to grow into them as your business grows. The email builder is excellent. You can also use your own HTML. I use a product called "MailStyler" for a few of my business projects and I can add the HTML into Acumbamail without any issues.
I bought the 3rd tier with a few of my better clients in mind. The form builder works great, so I can easily duplicate their existing forms and move their subs over to Acumbamail. The landing page builder and white label option tick all the boxes for my business. This is one of the better products you'll find on AppSumo.