The best alternatives to UseINBOX are Email Christmas Tree, Mailzak, and Email Kick. If these 3 options don't work for you, we've listed a few more alternatives below.
Mailzak powers your marketing campaigns without you making much efforts. With mailzak, email marketing is more than just sending mail. It takes into consideration how user behaves with those emails
Connect your Amazon SES directly and build design elegant, mobile responsive emails using drag & drop email editor and get analytics for your email. Lower cost and get a complete analytics on your emails.
Design your Email Templates without writing a line of code. Modules Composer is one of the easiest email builders to use for email design production with 30 ESP export option including Mailchimp, Klaviyo & more!