Aimhigh HTML Form 2 Mail (AHF2M)

AHF2M is a WordPress plugin that exposes a configurable public URL where visitors can POST a plain HTML form. Submissions are sanitized, never stored in the database, and sent to a recipient as an HTML email using your template (admin HTML and/or files under templates/).

Use cases include Elementor “HTML” widgets, block editor Custom HTML, or any theme template where you control the form markup.

Requirements

• WordPress 6.0 or higher (see plugin header).
• PHP 7.4 or higher (see plugin header).
• Pretty permalinks (or equivalent) so the custom rewrite endpoint resolves. After install or endpoint changes, flush permalinks once (see Installation).

Installation

1. Copy the ahf2m folder into wp-content/plugins/.
2. In Plugins, activate Custom Form 2 Mail.
3. Go to Settings → Permalinks and click Save Changes (no need to edit anything). This registers the form endpoint with WordPress.
4. Open Settings → AHF2M and configure the endpoint, recipient, and optional custom HTML template.

Quick start (site owners)

1. Settings → AHF2M
   Note the URL shown at the top (e.g. https://example.com/ahf2m/). That is your form action.
2. Build a form with method="post" and action pointing to that URL (trailing slash is fine).
3. Use name attributes on inputs; those names drive {{placeholder}} replacement in email templates.
4. Add the nonce and honeypot fields (recommended; see Special form fields).
5. Submit the form. The browser receives a JSON response (see HTTP response).

Settings (Settings → AHF2M)

The settings page also shows the exact form action URL for your site.

Special form fields

These name values are reserved; they are not included in the emailed field list as regular data (except where noted).

Shortcode for nonce (in a post/page):

[ahf2m_nonce_field]

Renders the hidden fields WordPress needs for ahf2m_submit_form.

Honeypot example (hide from users, keep empty):

<input
  type="text"
  name="ahf2m_hp"
  value=""
  style="display:none !important;"
  tabindex="-1"
  autocomplete="off"
/>

Placeholders

Placeholders are resolved in email templates only (custom HTML in settings and/or templates/*.html). The plain HTML table fallback does not interpret these tokens (except it does not use templates at all).

1. Form field placeholders — {{placeholder}}

Syntax: double curly braces, optional spaces inside braces.

• Pattern: {{field_name}}
• Meaning: Replaced with the sanitized value of the submitted field whose name matches, after WordPress sanitize_key() rules (lowercase, only a-z, 0-9, _, -).

Examples:

• Form: <input name="first_name" /> → use {{first_name}}
• Form: <input name="availability-date" /> → use {{availability-date}} (hyphen allowed in placeholder token)

If the field was not submitted or is empty after sanitization, the placeholder is replaced with N/A.

Important: HTML in field values is not interpreted as HTML in the email; values are output with esc_html() for safety.

2. Built-in “merge” placeholders — same {{ }} syntax

These are not taken from the form; they are injected by the plugin:

3. Static literals — [timestamp] and [ip]

These use square brackets (not curly braces):

Replaced after {{ }} processing; values are escaped for HTML.

Template resolution order

The email body is built in this order:

1. Custom email HTML (Settings → AHF2M)
   If the textarea is not empty (after trim), it is used for every submission. File templates are ignored in this case.

2. File templates (only when custom HTML is empty)

   • wp-content/plugins/ahf2m/templates/{template_name}.html
     where template_name comes from the POST field template_name (default default).
   • If that file is missing, templates/default.html, then templates/Default.html (for case-sensitive servers).

3. Fallback
   If no template file exists, a simple HTML table of all submitted fields (keys and values) is sent.

Example HTML form

<form method="post" action="https://example.com/ahf2m/">
  <!-- If you use the shortcode on a page, paste the rendered nonce fields here instead -->
  <input type="hidden" name="ahf2m_nonce" value="..." />
  <input type="hidden" name="_wp_http_referer" value="..." />

  <input
    type="text"
    name="ahf2m_hp"
    value=""
    style="display:none !important;"
    tabindex="-1"
    autocomplete="off"
  />

  <input type="hidden" name="template_name" value="default" />

  <label>First name <input type="text" name="first_name" required /></label>
  <label>Email <input type="email" name="email" required /></label>
  <button type="submit">Send</button>
</form>

Point action at your real endpoint from Settings → AHF2M.

HTTP response

Successful and error responses use wp_send_json(): JSON body and appropriate HTTP status code.

Typical shape:

{
  "success": true,
  "message": "Form submitted successfully."
}

Common status codes: 200 success, 400 honeypot/invalid, 403 origin or nonce failure, 405 not POST, 429 rate limit, 500 mail failure.

Note: Normal HTML form navigation will show JSON in the browser. For a smooth UX, submit via JavaScript (fetch / XMLHttpRequest) and handle the JSON, or add your own redirect flow later.

Security behavior (summary)

• POST only at the endpoint.
• Same-origin check using Origin / Referer host vs site host when those headers are present; if both are missing, the request may still be allowed (defense in depth elsewhere).
• Optional nonce when ahf2m_nonce is posted.
• Honeypot ahf2m_hp.
• Per-IP rate limit: 5 submissions per minute (transient-based).
• Input sanitization by field name heuristics (email, url/website, message/comment, etc.) and sanitize_key for names.
• No submission rows written to the WordPress database.

Email delivery

• Transport: WordPress wp_mail() (respects SMTP plugins if configured).
• Format: HTML (Content-Type: text/html; charset=UTF-8).
• Subject: Localized string [AHF2M] New form submission (filterable in code if you extend the plugin).

Troubleshooting

For contributors

Repository layout

ahf2m/
├── ahf2m.php          # Main plugin bootstrap + AHF2M_Plugin class
├── templates/        # Optional .html file templates (e.g. default.html)
└── README.md         # This file

Architecture

• Single class: AHF2M_Plugin (final) in ahf2m.php.
• Rewrite: add_rewrite_rule() maps ^{endpoint}/?$ → index.php?ahf2m_action=submit.
• Query var: ahf2m_action registered via query_vars; value submit triggers the handler.
• Handler: template_redirect → maybe_handle_submission().
• Admin: options.php group ahf2m_settings; menu under Settings → AHF2M.

Design choices worth preserving

1. No DB writes for form payloads—privacy and simplicity.
2. Strict file reads under templates/ using realpath() and basename allowlists.
3. Template rendering separates {{ }} (escaped values) from [timestamp] / [ip] (literal tokens).
4. Options: use register_setting + sanitize callbacks; endpoint changes hook update_option_ahf2m_endpoint to flush rewrites.

How to extend safely

• Prefer wp_mail filters (e.g. wp_mail, wp_mail_from) for from-address or headers rather than editing core flow unless necessary.
• New placeholders: extend normalize_template_data() and/or apply_builtin_template_tokens(); document them in this README.
• i18n: strings use __() / esc_html__() with text domain ahf2m; add a languages/ catalog if you ship translations.

Coding standards

• Follow WordPress PHP Coding Standards where practical.
• Keep changes focused; avoid unrelated refactors in the same PR as a feature fix.

Pull requests

1. Describe behavior change and testing steps (WP version, PHP version).
2. Confirm permalinks / endpoint still work after your change.
3. If you add settings, update this README and the settings screen help text.

License

This plugin is licensed under the GPL-2.0-or-later (see plugin header and License URI in ahf2m.php).

Credits

Maintained by Eric Aimhigh and contributors. Issues and PRs welcome on the plugin’s GitHub repository (see Plugin URI in ahf2m.php).