hMailServer

Projects that follow the best practices below can voluntarily self-certify and show that they've achieved an Open Source Security Foundation (OpenSSF) best practices badge.

There is no set of practices that can guarantee that software will never have defects or vulnerabilities; even formal methods can fail if the specifications or assumptions are wrong. Nor is there any set of practices that can guarantee that a project will sustain a healthy and well-functioning development community. However, following best practices can help improve the results of projects. For example, some practices enable multi-person review before release, which can both help find otherwise hard-to-find technical vulnerabilities and help build trust and a desire for repeated interaction among developers from different companies. To earn a badge, all MUST and MUST NOT criteria must be met, all SHOULD criteria must be met OR be unmet with justification, and all SUGGESTED criteria must be met OR unmet (we want them considered at least). If you want to enter justification text as a generic comment, instead of being a rationale that the situation is acceptable, start the text block with '//' followed by a space. Feedback is welcome via the GitHub site as issues or pull requests There is also a mailing list for general discussion.

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These are the Gold level criteria. You can also view the Passing or Silver level criteria.

Baseline Series: Baseline Level 1 Baseline Level 2 Baseline Level 3

        

 Basics 5/5 ●

  • General

    Note that other projects may use the same name.

    hMailServer is a free, open-source mail server for Windows and Linux, implementing SMTP, IMAP and POP3, with webmail, a REST API and a Control Panel. It is a maintained fork of Martin Knafve's hMailServer, brought up to date with a current toolchain, current cryptography, and the transport-security and authentication standards expected of a mail server in 2026.

    Please use SPDX license expression format; examples include "Apache-2.0", "BSD-2-Clause", "BSD-3-Clause", "GPL-2.0+", "LGPL-3.0+", "MIT", and "(BSD-2-Clause OR Ruby)". Do not include single quotes or double quotes.
    If there is more than one language, list them as comma-separated values (spaces optional) and sort them from most to least used. If there is a long list, please list at least the first three most common ones. If there is no language (e.g., this is a documentation-only or test-only project), use the single character "-". Please use a conventional capitalization for each language, e.g., "JavaScript".
    The Common Platform Enumeration (CPE) is a structured naming scheme for information technology systems, software, and packages. It is used in a number of systems and databases when reporting vulnerabilities.

    This entry replaces https://www.bestpractices.dev/en/projects/14187, which was made through a GitHub login. GitHub suspended the project account on 18 September 2026, so that entry can no longer be edited. The project has lived on GitLab since 22 September 2026: https://gitlab.com/Progressiverobot/hmailserver. Every answer here was checked again against the project on 26 September 2026.

  • Prerequisites


    Enough for a badge!

    The project MUST achieve a silver level badge. [achieve_silver]

  • Project oversight


    Enough for a badge!

    The project MUST have a "bus factor" of 2 or more. (URL required) [bus_factor]
    A "bus factor" (aka "truck factor") is the minimum number of project members that have to suddenly disappear from a project ("hit by a bus") before the project stalls due to lack of knowledgeable or competent personnel. The truck-factor tool can estimate this for projects on GitHub. For more information, see Assessing the Bus Factor of Git Repositories by Cosentino et al.

    GOVERNANCE.md names two maintainers but says the record of knowing the codebase is still one person's. In the past year all but one human commit on master are Christopher Holloway's; the second maintainer, Zain Ul Abidin (a Developer on GitLab), has one. Only the owner's account can push master or create release tags. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/GOVERNANCE.md#continuity


    Enough for a badge!

    The project MUST have at least two unassociated significant contributors. (URL required) [contributors_unassociated]
    Contributors are associated if they are paid to work by the same organization (as an employee or contractor) and the organization stands to benefit from the project's results. Financial grants do not count as being from the same organization if they pass through other organizations (e.g., science grants paid to different organizations from a common government or NGO source do not cause contributors to be associated). Someone is a significant contributor if they have made non-trivial contributions to the project in the past year. Examples of good indicators of a significant contributor are: written at least 1,000 lines of code, contributed 50 commits, or contributed at least 20 pages of documentation.

    There are not two unassociated significant contributors. In the past year Christopher Holloway (Progressive Robot Ltd) wrote about 1,400 of the commits on master, under three identities. Zain Ul Abidin, of the same company, wrote one, and dependabot wrote 10 automated commits. https://gitlab.com/Progressiverobot/hmailserver/-/graphs/master


  • Other


    Enough for a badge!

    The project MUST include a license statement in each source file. This MAY be done by including the following inside a comment near the beginning of each file: SPDX-License-Identifier: [SPDX license expression for project]. [license_per_file]
    This MAY also be done by including a statement in natural language identifying the license. The project MAY also include a stable URL pointing to the license text, or the full license text. Note that the criterion license_location requires the project license be in a standard location. See this SPDX tutorial for more information about SPDX license expressions. Note the relationship with copyright_per_file, whose content would typically precede the license information.

    Every project source file carries 'SPDX-License-Identifier: AGPL-3.0-or-later' in its opening comment. Anyone can check this with python build/add-license-headers.py --check, which passes on master. Vendored third-party sources under their own licences (zlib and QuickJS) and MIDL-generated files are skipped on purpose. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/build/add-license-headers.py


 Change Control 4/4 ●

  • Public version-controlled source repository


    Enough for a badge!

    The project's source repository MUST use a common distributed version control software (e.g., git or mercurial). [repo_distributed]
    Git is not specifically required and projects can use centralized version control software (such as subversion) with justification.

    The repository is git, a distributed version control system, hosted on GitLab: https://gitlab.com/Progressiverobot/hmailserver


    Enough for a badge!

    The project MUST clearly identify small tasks that can be performed by new or casual contributors. (URL required) [small_tasks]
    This identification is typically done by marking selected issues in an issue tracker with one or more tags the project uses for the purpose, e.g., up-for-grabs, first-timers-only, "Small fix", microtask, or IdealFirstBug. These new tasks need not involve adding functionality; they can be improving documentation, adding test cases, or anything else that aids the project and helps the contributor understand more about the project.

    Small, bounded tasks for new or casual contributors carry the 'good first issue' label on the GitLab tracker, and each says where to look, how to check it and what done means (CONTRIBUTING.md, 'Small tasks'). Two are open today, #18 and #26. https://gitlab.com/Progressiverobot/hmailserver/-/issues/?label_name%5B%5D=good%20first%20issue


    Enough for a badge!

    The project MUST require two-factor authentication (2FA) for developers for changing a central repository or accessing sensitive data (such as private vulnerability reports). This 2FA mechanism MAY use mechanisms without cryptographic mechanisms such as SMS, though that is not recommended. [require_2FA]

    The project requires two-factor authentication of every account that can change the central repository or read private vulnerability reports, and each has it on. Those accounts are the three members of the GitLab project: Progressiverobot, the Owner and the only account that may push master, batch* branches or v* tags; and zainulabidin1990 and chrisholloway5, Developers, who can push other branches and read confidential issues. GOVERNANCE.md names who holds each role: https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/GOVERNANCE.md


    Enough for a badge!

    The project's two-factor authentication (2FA) SHOULD use cryptographic mechanisms to prevent impersonation. Short Message Service (SMS) based 2FA, by itself, does NOT meet this criterion, since it is not encrypted. [secure_2FA]
    A 2FA mechanism that meets this criterion would be a Time-based One-Time Password (TOTP) application that automatically generates an authentication code that changes after a certain period of time. Note that GitHub supports TOTP.

    The project's accounts authenticate on GitLab, whose two-factor authentication offers only cryptographic mechanisms: a TOTP authenticator app or a WebAuthn device or passkey. SMS is not offered, so the 2FA in use cannot be SMS.


 Quality 7/7 ●

  • Coding standards


    Enough for a badge!

    The project MUST document its code review requirements, including how code review is conducted, what must be checked, and what is required to be acceptable. (URL required) [code_review_standards]
    See also two_person_review and contribution_requirements.

    CONTRIBUTING.md (Merge requests, Change checklists) says how review is done: the maintainer reads the change, asks for changes on the merge request, and runs the full Windows regression gate before anything lands. The merge request template lists what a change must meet: a /WX build, a regression test (for a fix, one that fails before it), parameterised SQL, the schema and settings checklists, licence headers and regenerated files. RELEASE.md step 2 adds an adversarial review of the whole diff before each release. GitLab has no approval rule configured. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/CONTRIBUTING.md#merge-requests


    Enough for a badge!

    The project MUST have at least 50% of all proposed modifications reviewed before release by a person other than the author, to determine if it is a worthwhile modification and free of known issues which would argue against its inclusion [two_person_review]

    One active maintainer lands changes, and GitLab has no approval rule configured on the project (CONTRIBUTING.md, 'Merge requests'). Changes are reviewed adversarially by AI agents and held by fixture tests and the full regression gate before they land, but that is not review by a second person, so fewer than half of the changes are reviewed by someone other than the author. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/CONTRIBUTING.md#merge-requests


  • Working build system


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    The project MUST have a reproducible build. If no building occurs (e.g., scripting languages where the source code is used directly instead of being compiled), select "not applicable" (N/A). (URL required) [build_reproducible]
    A reproducible build means that multiple parties can independently redo the process of generating information from source files and get exactly the same bit-for-bit result. In some cases, this can be resolved by forcing some sort order. JavaScript developers may consider using npm shrinkwrap and webpack OccurrenceOrderPlugin. GCC and clang users may find the -frandom-seed option useful. The build environment (including the toolset) can often be defined for external parties by specifying the cryptographic hash of a specific container or virtual machine that they can use for rebuilding. The reproducible builds project has documentation on how to do this.

    Builds repeat on one machine (build_repeatable), but nobody has independently rebuilt a release to the same bytes. RELEASE.md step 8 says what that needs: the same toolchain (v145, Windows SDK 10.0.26100) and library layout. Release integrity rests on Authenticode signatures and, through 6.3.3, Sigstore bundles; 6.3.4 carries Authenticode only. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/RELEASE.md


  • Automated test suite


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    A test suite MUST be invocable in a standard way for that language. (URL required) [test_invocation]
    For example, "make check", "mvn test", or "rake test" (Ruby).

    The Linux suite and the .NET unit tests run with the language's standard command, dotnet test (for example dotnet test hmailserver/test/LinuxRegressionTests -c Release). The Windows suite, which needs the service registered on a bench, runs under NUnit's console runner through build\run-tests.ps1, as CONTRIBUTING.md's Testing section documents. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/CONTRIBUTING.md#testing


    Enough for a badge!

    The project MUST implement continuous integration, where new or changed code is frequently integrated into a central code repository and automated tests are run on the result. (URL required) [test_continuous_integration]
    In most cases this means that each developer who works full-time on the project integrates at least daily.

    Changes are integrated on batch branches and fast-forwarded to master, and every batch lands only after the maintainer's own full regression gate on the result: the whole Windows suite split across two machines, plus the whole Linux suite. .gitlab-ci.yml defines the same builds and suites on the project's own runners (linix, bench150) for master, batch* and v* tags, but no full pipeline has run on GitLab yet (issue #21); until 18 September 2026 GitHub Actions ran them. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/hmailserver/docs/ContinuousIntegration.md


    Enough for a badge!

    The project MUST have FLOSS automated test suite(s) that provide at least 90% statement coverage if there is at least one FLOSS tool that can measure this criterion in the selected language. [test_statement_coverage90]

    The only measured figure is 73.48% of the native server's lines over the whole Windows regression suite (OpenCppCoverage 0.9.9, 15 September 2026), below 90%. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/ASSURANCE-CASE.md


    Enough for a badge!

    The project MUST have FLOSS automated test suite(s) that provide at least 80% branch coverage if there is at least one FLOSS tool that can measure this criterion in the selected language. [test_branch_coverage80]

    Branch coverage is not measured. The native server's coverage was measured once, on 15 September 2026, with OpenCppCoverage 0.9.9, which has no branch mode, so only a line figure exists (73.48%); FLOSS tools that measure branches exist (clang's source-based coverage), so N/A does not apply. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/ASSURANCE-CASE.md


 Security 5/5 ●

  • Use basic good cryptographic practices

    Note that some software does not need to use cryptographic mechanisms. If your project produces software that (1) includes, activates, or enables encryption functionality, and (2) might be released from the United States (US) to outside the US or to a non-US-citizen, you may be legally required to take a few extra steps. Typically this just involves sending an email. For more information, see the encryption section of Understanding Open Source Technology & US Export Controls.

    Enough for a badge!

    The software produced by the project MUST support secure protocols for all of its network communications, such as SSHv2 or later, TLS1.2 or later (HTTPS), IPsec, SFTP, and SNMPv3. Insecure protocols such as FTP, HTTP, telnet, SSLv3 or earlier, and SSHv1 MUST be disabled by default, and only enabled if the user specifically configures it. If the software produced by the project does not support network communications, select "not applicable" (N/A). [crypto_used_network]

    SMTP, IMAP and POP3 support STARTTLS and implicit TLS. A new installation gets a certificate, offers STARTTLS on 25, 587, 110 and 143, and requires TLS for authentication from the Internet (SecureDefaults.md); a database that is upgraded or attached keeps its previous settings. The REST API (bound to 127.0.0.1) and the web-services listeners are off by default. The SNMP agent is off by default and speaks SNMPv3 authPriv, with v2c a separate opt-in. Outbound delivery supports DANE, MTA-STS and per-domain TLS policy. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/hmailserver/docs/SecureDefaults.md


    Enough for a badge!

    The software produced by the project MUST, if it supports or uses TLS, support at least TLS version 1.2. Note that the predecessor of TLS was called SSL. If the software does not use TLS, select "not applicable" (N/A). [crypto_tls12]

    TLS 1.2 and 1.3 are the versions a new database enables (SslVersions 24). SSLv2 and SSLv3 cannot be enabled, and TLS 1.0 and 1.1 only by an explicit setting. The regression suite runs TLS 1.2 and 1.3 handshakes (RegressionTests/SSL/SslTlsVersionTests.cs). https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/hmailserver/source/Server/Common/TCPIP/SslContextInitializer.cpp


  • Secured delivery against man-in-the-middle (MITM) attacks


    Enough for a badge!

    The project website, repository (if accessible via the web), and download site (if separate) MUST include key hardening headers with nonpermissive values. (URL required) [hardened_site]
    Note that GitHub and GitLab are known to meet this. Sites such as https://securityheaders.com/ can quickly check this. The key hardening headers are: Content Security Policy (CSP), HTTP Strict Transport Security (HSTS), X-Content-Type-Options (as "nosniff"), and X-Frame-Options. Fully static web sites with no ability to log in via the web pages could omit some hardening headers with less risk, but there's no reliable way to detect such sites, so we require these headers even if they are fully static sites.

    The repository and download site, gitlab.com, sends Content-Security-Policy, Strict-Transport-Security, X-Content-Type-Options: nosniff and X-Frame-Options: SAMEORIGIN. The project page https://www.progressiverobot.com/hmailserver-services/ sends all four, with HSTS preload and includeSubDomains; both were checked on 26 September 2026. https://gitlab.com/Progressiverobot/hmailserver


  • Other security issues


    Enough for a badge!

    The project MUST have performed a security review within the last 5 years. This review MUST consider the security requirements and security boundary. [security_review]
    This MAY be done by the project members and/or an independent evaluation. This evaluation MAY be supported by static and dynamic analysis tools, but there also must be human review to identify problems (particularly in design) that tools cannot detect.

    The maintainers reviewed the current codebase's security in 2026, and the review is documented in ASSURANCE-CASE.md, written in August 2026 and last revised on 25 September 2026. It covers the security requirements (claims C1-C7), the threat model and the security boundary (trust boundaries B1-B6), the design argument, a CWE-mapped weakness analysis and the residual risks. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/ASSURANCE-CASE.md


    Enough for a badge!

    Hardening mechanisms MUST be used in the software produced by the project so that software defects are less likely to result in security vulnerabilities. (URL required) [hardening]
    Hardening mechanisms may include HTTP headers like Content Security Policy (CSP), compiler flags to mitigate attacks (such as -fstack-protector), or compiler flags to eliminate undefined behavior. For our purposes least privilege is not considered a hardening mechanism (least privilege is important, but separate).

    The Windows server is built with the MSVC hardening defaults left on (/GS, DEP, ASLR) and with Control Flow Guard (/guard:cf) in every configuration of hMailServer.vcxproj. The web pages it serves send Content-Security-Policy and X-Frame-Options: DENY, and unsafe password-hash schemes are refused for new secrets. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/hmailserver/source/Server/hMailServer/hMailServer.vcxproj


 Analysis 2/2 ●

  • Dynamic code analysis


    Enough for a badge!

    The project MUST apply at least one dynamic analysis tool to any proposed major production release of the software produced by the project before its release. [dynamic_analysis]
    A dynamic analysis tool examines the software by executing it with specific inputs. For example, the project MAY use a fuzzing tool (e.g., American Fuzzy Lop) or a web application scanner (e.g., OWASP ZAP or w3af). In some cases the OSS-Fuzz project may be willing to apply fuzz testing to your project. For purposes of this criterion the dynamic analysis tool needs to vary the inputs in some way to look for various kinds of problems or be an automated test suite with at least 80% branch coverage. The Wikipedia page on dynamic analysis and the OWASP page on fuzzing identify some dynamic analysis tools. The analysis tool(s) MAY be focused on looking for security vulnerabilities, but this is not required.

    Before each minor release, RELEASE.md step 8c fuzzes every libFuzzer harness of the MIME parser, under AddressSanitizer, for 30 minutes on the release source, and the release notes record the run (6.3.0 and 6.3.2; a patch release with no parser change cites the previous run, as 6.3.1 did). Step 8b also runs the whole regression suite on the assertion build. https://gitlab.com/Progressiverobot/hmailserver/-/releases/v6.3.2


    Enough for a badge!

    The project SHOULD include many run-time assertions in the software it produces and check those assertions during dynamic analysis. [dynamic_analysis_enable_assertions]
    This criterion does not suggest enabling assertions during production; that is entirely up to the project and its users to decide. This criterion's focus is instead to improve fault detection during dynamic analysis before deployment. Enabling assertions in production use is completely different from enabling assertions during dynamic analysis (such as testing). In some cases enabling assertions in production use is extremely unwise (especially in high-integrity components). There are many arguments against enabling assertions in production, e.g., libraries should not crash callers, their presence may cause rejection by app stores, and/or activating an assertion in production may expose private data such as private keys. Beware that in many Linux distributions NDEBUG is not defined, so C/C++ assert() will by default be enabled for production in those environments. It may be important to use a different assertion mechanism or defining NDEBUG for production in those environments.

    RELEASE.md step 8b runs the whole regression suite on the assertion build (build.ps1 -Configuration Release -Asserts), which keeps every HM_ASSERT; a violated assertion is logged as HM6364 and fails the test. That build is never shipped. https://gitlab.com/Progressiverobot/hmailserver/-/blob/master/RELEASE.md



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Project badge entry owned by: christopher holloway.
Entry created on 2026-09-26 05:28:20 UTC, last updated on 2026-09-26 06:16:51 UTC. Last achieved passing badge on 2026-09-26 05:45:21 UTC.