Mailjet

Mailjet is a well-established email service provider with a free tier offering 6000 emails per month (200 per day). You get both transactional and marketing email features, SMTP and API access, and a visual template builder if you need it. The free plan includes basic event tracking and compliance tools, so you can monitor delivery and stay on top of regulatory requirements.

Mailjet works well for teams that want a balanced service: professional enough for production transactional mail, flexible enough for marketing campaigns, and simple enough not to require a dedicated email engineer. The free tier is realistic for small to medium businesses, and the pricing is straightforward when you grow.