Billionmail
BillionMail gives you open-source MailServer, NewsLetter, Email Marketing — fully self-hosted, dev-friendly, and free from monthly fees. Join the discord: https://discord.gg/asfXzBUhZr
forwardemail
Privacy-focused encrypted email for everyone. All-in-one alternative to Gmail + Mailchimp + Sendgrid.
Mindbaz
Awesome Opensource Email Resources