1.stalwartlabs / stalwart
All-in-one Mail & Collaboration server. Secure, scalable and fluent in every protocol (IMAP, JMAP, SMTP, CalDAV, CardDAV, WebDAV).
+328 stars
from 15,297 · score 5.80
Trending repositories
Ranked by Attention Score: stars gained over the last 7 complete days
24 repositories by Attention Score · Oct 27, 2026 – Nov 2, 2026 (UTC)
2.Billionmail / 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
+193 stars
from 15,953 · score 5.27
3.knadh / listmonk
High performance, self-hosted, newsletter and mailing list manager with a modern dashboard. Single binary app.
+139 stars
from 23,971 · score 4.94
4.flectar / mail
Built from the ground up for speed. Flectar Mail delivers native performance, instant startup, and as little as 80 MB of RAM.
+109 stars
from 1,616 · score 4.70
5.pppscn / SmsForwarder
短信转发器——监控Android手机短信、来电、APP通知，并根据指定规则转发到其他手机：钉钉群自定义机器人、钉钉企业内机器人、企业微信群机器人、飞书机器人、企业微信应用消息、邮箱、bark、webhook、Telegram机器人、Server酱、PushPlus、手机短信等。包括主动控制服务端与客户端，让你轻松远程发短信、查短信、查通话、查话簿、查电量等。（V3.0 新增）PS.这个APK主要是学习与自用，如有BUG请提ISSUE，同时欢迎大家提PR指正
+104 stars
from 28,584 · score 4.65
6.docker-mailserver / docker-mailserver
Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container.
+35 stars
from 19,680 · score 3.58
7.mailcow / mailcow-dockerized
mailcow: dockerized - 🐮 + 🐋 = 💕
+33 stars
from 13,694 · score 3.53
8.postalserver / postal
📮 A fully featured open source mail delivery platform for incoming & outgoing e-mail
+19 stars
from 16,893 · score 3.00
9.cypht-org / cypht
Cypht: Lightweight Open Source webmail aggregator [PHP, JS]. Supports IMAP/SMTP, JMAP and EWS (Exchange Web Services)
+16 stars
from 1,771 · score 2.83
10.PHPMailer / PHPMailer
The classic email sending library for PHP
+10 stars
from 22,332 · score 2.40
11.forwardemail / forwardemail.net
Privacy-focused encrypted email for everyone. All-in-one alternative to Gmail + Mailchimp + Sendgrid.
+8 stars
from 1,691 · score 2.20
12.jstedfast / MailKit
A cross-platform .NET library for IMAP, POP3, and SMTP.
+7 stars
from 6,863 · score 2.08
13.wneessen / go-mail
📧 Easy to use, yet comprehensive library for sending mails with Go
+6 stars
from 1,503 · score 1.95
14.Mailu / Mailu
Insular email distribution - mail server as Docker images
+4 stars
from 7,592 · score 1.61
15.twisted / twisted
Event-driven networking engine written in Python.
+4 stars
from 5,995 · score 1.61
16.dovecot / core
Dovecot mail server
+4 stars
from 1,271 · score 1.61
17.mail-in-a-box / mailinabox
Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box.
+3 stars
from 15,449 · score 1.39
18.haraka / Haraka
A fast, highly extensible, and event driven SMTP server
+3 stars
from 5,627 · score 1.39
19.lukencode / FluentEmail
All in one email sender for .NET. Supports popular senders (SendGrid, MailGun, etc) and Razor templates.
+3 stars
from 3,215 · score 1.39
20.AfterShip / email-verifier
:white_check_mark: A Go library for email verification without sending any emails.
+2 stars
from 1,648 · score 1.10
21.foxcpp / maddy
✉️ Composable all-in-one mail server.
+1 stars
from 6,115 · score 0.69
22.cosullivan / SmtpServer
A SMTP Server component written in C#
+1 stars
from 827 · score 0.69
23.mguessan / davmail
DavMail POP/IMAP/SMTP/CalDAV/CardDAV/LDAP Exchange and Office 365 Gateway - Synced with main subversion repository at
+1 stars
from 773 · score 0.69
24.danzuep / MailKitSimplified
Send and receive emails easily, fluently, with one line of code for each operation.
+1 stars
from 97 · score 0.69