To make sure you're only sending emails to the people who want to read them, clean up your email list so that it excludes recipients who haven't opened a certain amount of emails in the campaign's recent history. This makes sure your emails' open and clickthrough rates reflect only your most interested readers, allowing you to collect more effective data on what is and isn't working in each email you send.
Marketing emails need to be personalized to the reader and filled with interesting graphics. Few people want to read emails that are addressed "Dear Sir/Madam" -- as opposed to their first or last name -- and even fewer people want to read an email that simply gives them a wall of text. Visuals help your recipients quickly understand what the point of the email is.
I recently had my MailChimp account suspended. One of my sites is in the ‘make money online’ space. It’s a completely legitimate website, but apparently if your emails contain keywords they don’t like, they will suspend you. I would not recommend using them. Contacting support I just get form responses that are completely unhelpful. There’s no phone support- just account termination. Really bad experience. Luckily, this is a very new site- but imagine if you have thousands of emails and they just shut you down without ANY recourse.
Drip offers a very small forever free plan, along with a two-week free trial for the Basic and Pro membership levels. If you choose to continue service after those two weeks, then your card will be charged. There is a 30-day refund window from when you start your service, but it’s up to the discretion of Drip whether you will receive a full refund.