Haltman mail-forwarding-core

Overview

Haltman mail-forwarding-core is an open-source email-forwarding service and the reference stack behind Haltman.io’s public service. It suits people who want free, API-managed aliases or are prepared to operate their own mail infrastructure. Its strongest case is uncapped forwarding; it is a poor fit if you need a mailbox or want to reply from an alias.

Key features

Users choose a handle, domain and destination, then confirm the forwarding rule by email. Custom domains and API access make the service useful for managing aliases programmatically, but it does not offer catch-all forwarding. Messages go to an external destination rather than a local inbox, so this is a forwarding layer, not an alternative email account.

The stack brings together Postfix, Dovecot, PostSRSd, MariaDB and DNS configuration, with optional OpenDKIM signing. Its NestJS API manages alias rules, and API keys support programmatic administration. A Firefox extension is also available; its maker says it encrypts the API key locally using AES-GCM and PBKDF2 key derivation. The extension is useful for Firefox users, but there is no mobile app for the service.

The reference setup uses recipient allowlisting, sender anti-spoofing and rate limits on connections, messages and recipients. Authenticated submission requires TLS and Dovecot SASL; PostSRSd rewrites forwarded senders, and inbound SRS-formatted senders are rejected. Confirmation tokens are six digits, stored as SHA-256 hashes and set to expire after 10 minutes. The project says it avoids logging message content and storing plaintext tokens in the database. Optional OpenDKIM signing fails closed if enabled but unavailable.

Those controls make the project a more considered foundation than a bare forwarding rule, but they do not guarantee delivery: strict DMARC rejection policies can disrupt forwarding, and shared domain reputation can affect results. Most importantly, replies cannot be sent from an alias, and replying may expose the real address. There is no message storage or PGP.

Pricing

The Free plan costs nothing, billed with no payment. It includes unlimited forwarding rules, users, addresses, domains and emails, plus API access and custom domains. There is no free trial because the plan is free. The trade-off is not a lower quota tier but the product’s forwarding-only scope: no catch-all forwarding, stored mailbox, or reply-from-alias. Choose it for cost-free forwarding without stated usage caps; look elsewhere if those missing email functions are essential.

Platforms

Haltman mail-forwarding-core supports API, extension, Linux, self-hosted and web use. Running the stack yourself requires Debian 13 or compatible, root or sudo access, a public IP with port 25 open, and DNS control for each forwarded domain. Those prerequisites give technically capable operators control over deployment, but make self-hosting a substantial commitment rather than a turnkey option. The project is released under the Unlicense, which its maker describes as public domain.

Who it's for

This is best for people who need privacy-oriented forwarding for research, education or legitimate personal use, and for operators comfortable administering mail infrastructure. It is not the right choice for anyone who needs a full mailbox, PGP, mobile service access or reliable alias-based replies.

Pros and cons

• Pros: The free plan has no stated caps on rules, users, addresses, domains or forwarded emails, making it suitable for broad forwarding needs without a paid tier.
• Pros: API management and a Firefox extension offer practical ways to handle aliases, with local encryption for the extension’s API key.
• Pros: The reference configuration combines TLS-required submission, anti-spoofing, allowlisting and rate limits rather than relying on forwarding alone.
• Cons: There is no mailbox storage, so users must rely on an external destination for every message.
• Cons: Replies cannot come from the alias and may reveal the real address, limiting use for ongoing correspondence.
• Cons: Self-hosting needs a public mail server, open port 25 and domain-level DNS control; forwarding can also face DMARC and shared-reputation delivery problems.

Alternatives

Forward Email is worth considering if you want a freemium service with broader platform coverage, including Android, iOS, macOS and Windows, as well as self-hosting. Its company describes the service as built with 100% open-source software.

Forward is a closer alternative for someone who wants a hosted free tier with defined limits: one domain, 25 aliases, 500 forwards per day, seven days of logs and one team seat.

ImprovMX may suit users who prefer a hosted free plan with a stated 99% uptime guarantee, 25 aliases, 500 forwarded emails per day, seven-day email logs, API access and standard email and chat support.

MailerZ is an option if message storage matters more than unlimited forwarding: its free plan includes a 14-day message store, but is limited to one domain, three aliases and one seat, with sending, SMTP and API disabled.

DNSExit Email Forwarding is another freemium service, with its free plan applying to domains registered through DNSExit.

EForw offers a free tier with one domain and unlimited catch-all aliases, a better match for users who specifically need catch-all forwarding.

InboxMail is a freemium alternative with a free plan priced in euros and a broader set of email and campaign allowances.

KaiMail offers a free tier with one custom domain and one mailbox, for users who want a mailbox rather than forwarding alone.

For a wider comparison, see Email Forwarding Services.

Verdict

Choose Haltman mail-forwarding-core if you want free forwarding without stated rule or address caps, value API control, and can accept that messages live elsewhere. Its security-minded reference setup and self-hosting option are compelling for technically capable users. Look elsewhere if you need a mailbox, catch-all rules, mobile access or replies that keep your real address private.