Among others, Mailgun, SendGrid, and Mailjet are all used to send emails. They all have template builders, track deliverability, and have an API you can use to schedule emails.
It is important however that you identify whether you plan on sending transactional emails (to people who have business with you), marketing emails, or a combination of both. The distinction is required by most platforms these days as they have to adhere to countries' opt-in and opt-out requirements.
That said, it is not uncommon to mix an email delivery platform with a email template builder. Especially if you need to create a template that supports multiple languages or supports AMP for email (interactive emails). Such platforms range in price based upon the email delivery platforms they support, the template features they offer, and whether they offer multilingual support. For example:
- BEE is one of the cheaper and more widely accepted email template builders and has hundreds of templates you can use to begin with. It also has collaborative features so you can draft emails with others. It's perfect for people who want to create beautiful templates quickly.
- Stripo is another major email template builder. They offer many prebuilt templates and more advanced features than BEE. For example, Stripo supports some AMP for email features. This option is great for small and medium sized enterprises that want to send more engaging emails with little effort.
- Dyspatch is one the more expensive template builders. But it offers both a block building interface and a custom language used to build highly advanced templates. And it also offers full support for AMP emails and multilingual designs. A lot of SAAS companies tend to use it.
Note though that all of the email template builders listed work with different email delivery platforms. So you will need to pick a template builder that supports the API you plan on using. Some platforms allow you to copy and paste the final email code into the delivery platforms' template list and others have a built in publish interface.