Freshjet

People use SMTP or transactional email to prevent their email sent by wp_mail() fall into spam folder. And if you are using Mailjet as your transactional email, this plugin is probably the most convenient way to use Mailjet transactional email in WordPress.

Freshjet provide default wp_mail() functionality but super-power it with Mailjet. It's a drop-in replacement for wp_mail(). If you just send email without extra customization, likely you don't need to change your existing code.

And.. Freshjet supports Mailjet Passport Template. For documentation, visit Freshjet GitHub repository