update Postboi dkim template (MAIL FROM), add Postboi dkim-dmarc template

[darbymanning]

Description

Updates the templates for Postboi (postboi.email), follow-up to #1333.

postboi.email.dkim → version 2: adds an aligned Amazon SES custom MAIL FROM on the bounce subdomain (MX + SPFM) alongside the existing three DKIM CNAMEs. Also moves logoUrl to a URL hosted on the provider domain itself.

postboi.email.dkim-dmarc (new): identical to dkim v2 plus a starter DMARC monitoring policy (v=DMARC1; p=none;). Postboi only builds apply URLs for this template after checking via DNS that the domain publishes no existing DMARC record — domains with a policy are always sent to the plain dkim template instead, so an apply can never downgrade an existing p=quarantine/p=reject policy. The record additionally carries txtConflictMatchingMode: Prefix on v=DMARC1 and essential: OnApply.

Type of change

Please mark options that are relevant.

• New template (postboi.email.dkim-dmarc)
• Bug fix (non-breaking change which fixes an issue in the template)
• New feature (non-breaking change which adds functionality to the template) (postboi.email.dkim v2)
• Breaking change (fix or feature that would cause existing template behavior to be not backward compatible)

How Has This Been Tested?

Please mark the following checks done

• Template functionality checked using Online Editor
• Template file name follows the pattern <providerId>.<serviceId>.json
• resource URL provided with logoUrl is actually served by a webserver

Checklist of common problems

• syncPubKeyDomain is set — public key published at _dcpubkeyv1.postboi.email (unchanged from v1)
• warnPhishing is not set alongside syncPubKeyDomain — the two must not appear together
• syncRedirectDomain is set whenever the template uses redirect_uri in the synchronous flow
• no TXT record contains SPF content ("v=spf1 ...") — the MAIL FROM SPF uses SPFM on host bounce
• txtConflictMatchingMode is set on every TXT record that must be unique per label or content prefix — the DMARC record uses Prefix / v=DMARC1
• no variable is used as a bare full record value — DKIM variables are scoped with fixed suffixes (%dkim1%.dkim.amazonses.com)
• no bare variable is used as the full host label — hosts use fixed ._domainkey suffix
• no variable is used in the host field to create a subdomain — the bounce MAIL FROM host is a fixed label
• %host% does not appear explicitly in any host attribute
• essential is set to OnApply on records the end user may need to modify or remove without breaking the template — set on the DMARC record; the DKIM CNAMEs and MAIL FROM MX/SPFM are core to the service

Online Editor test results

Editor test link(s):

Test postboi.email/dkim-dmarc example.com/@

Test postboi.email/dkim-dmarc example.com/mail

Test postboi.email/dkim example.com/@

Test postboi.email/dkim example.com/mail

[github-actions]

✅ JSON Filename Check Passed

[github-actions]

✅ JSON Schema Validation Passed

[github-actions]

Linter OK

postboi.email.dkim-dmarc.json

Level	Code	Note

postboi.email.dkim.json

Level	Code	Note

[github-actions]

Linter passed all checks — approving for auto-merge.

[github-actions]

PR Description Check Passed

All required sections are filled in correctly.

Details

  OK  Type of change: 2/4 checkboxes ticked
  OK  How Has This Been Tested?: all 3 checkboxes ticked
  OK  Checklist of common problems: 10/10 checkboxes ticked
  OK  Online Editor test results: 4 link(s) found
  OK  Template coverage: all 2 template(s) covered
Labels to remove: Checklist of common problems not complete, Forged editor links, PR description incomplete, Test links missing

PR description check PASSED