Brevo
Free email marketing plan
Limits: 300 emails/day
Free Email tools
FeaturedYour tool here: Sponsor this spot, $19/mo (first month free)
Kit (ConvertKit)
Free plan for creators just starting out
Limits: Up to 10,000 subscribers
Mailchimp
Free marketing plan
Limits: 500 contacts, 1,000 sends/month
MailerLite
Free plan with campaigns, automations, a website, a landing page and signup forms
Limits: 250 subscribers, 2,500 emails/month, 2 seats; no API sending
Resend
Free transactional email API
Limits: 3,000 emails/month and 100/day (inbound counts too)