Aid4Mail
Aid4Mail is a fast, reliable, and highly accurate tool to collect, recover, search, and convert emails. It supports most mailbox file formats (e.g. PST, OST, OLM, mbox), IMAP accounts (e.g. Yahoo! Mail, AOL) and popular mail service providers (e.g. Microsoft 365, Exchange, Gmail). Aid4Mail can recover double-deleted messages and corrupted emails, and extract MIME data from certain types of unknown file formats through file carving.
Aid4Mail provides a large array of tools to search and filter out unwanted emails during conversion. Save time by using native pre-acquisition filters to download a subset of your mail from Exchange, Office 365, Gmail and other webmail services. Use Aid4Mail’s integrated search engine to cull-down your email collection. Its search operators are very similar to Gmail and Office 365.
Aid4Mail is used by Fortune 500 companies, government agencies and legal professionals around the world. It is made in Switzerland by perfectionists.
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Mailu
Mailu is a simple yet full-featured mail server as a set of Docker images. It is free software (both as in free beer & as in free speech), open to suggestions and external contributions. The project aims at providing people with an easily setup, easily maintained and full-featured mail server while not shipping proprietary software nor unrelated features often found in popular groupware.
Main features include:
Standard email server, IMAP and IMAP+, SMTP and Submission with autoconfiguration profiles for clients
Advanced email features, aliases, domain aliases, custom routing
Web access, multiple Webmails and administration interface
User features, aliases, auto-reply, auto-forward, fetched accounts
Admin features, global admins, announcements, per-domain delegation, quotas
Security, enforced TLS, DANE, MTA-STS, Letsencrypt!, outgoing DKIM, anti-virus scanner, Snuffleupagus, block malicious attachments
Antispam, auto-learn, greylisting, DMARC& SPF, anti-spoofing
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Hermes SEG
Hermes SEG is a free, open-source secure email gateway and server. It delivers spam, virus, and malware protection using SpamAssassin, ClamAV, and Amavisd-new, along with full encryption in transit and at rest via SMTP TLS, S/MIME, PGP, encrypted PDF (CipherMail), and Dovecot mail-crypt. It includes email archiving and integrated mailbox hosting with quotas, aliases, shared folders, Sieve rules, vacation replies, and mobile auto-configuration. Collaboration features come through Nextcloud (webmail, file sync, calendars, contacts). Identity and access are managed with OpenLDAP and Authelia, supporting SSO and MFA (TOTP, WebAuthn, Duo). It also enforces modern authentication standards: SPF, DKIM, DMARC, and ARC.
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lfr
lfr is self-hosted mail-server and newsletter software packaged as a single Go binary for Linux and macOS servers. It lets developers, self-hosters, and small teams host mailboxes for their domains, manage aliases and forwarding, search and reply to messages, and configure domain mail records. Newsletter tools support double-opt-in signup lists, Markdown-based issues, hosted archives and signup websites, one-click unsubscribe, bounce and complaint handling, and delivery through a configurable SMTP relay when direct sending is unavailable. The command-line interface runs locally or over SSH, with setup and diagnostic commands for server, DNS, and mail delivery tasks. lfr is distributed under the MIT license; the software itself is free, while users arrange and pay for their own server and any optional relay service.
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