List Growth, Signup Consent, and Preferences

Use this skill only after applying 00-email-marketing-guardrails (../00-email-marketing-guardrails/SKILL.md) to design or review first-party subscriber capture before campaign drafting, and treat it as operational guidance rather than legal advice. [ICO-01][ICO-02][MC-LISTS-01]

Consent-capture contract

• Apply 00-email-marketing-guardrails first and run 18-jurisdiction-compliance-routing before publishing a form; return HOLD while required routing facts are collectible and BLOCK when the applicable basis or capture requirement cannot be verified. [FTC-01][ICO-01][EU-EC-01][CRTC-CASL-01]
• Persist the contact identifier, signup source and form ID, exact consent statement and form version, timestamp, jurisdiction facts, channel, purpose, selected preferences, capture method, confirmation state, and later withdrawals or changes; do not reduce the audit trail to a generic consent flag. [ICO-CONSENT-01][KL-CONSENT-01][MC-PROFILE-01]
• Name the sender, channel, content or purpose, and expected frequency at capture, link the applicable privacy information, and use separate unbundled choices where purposes or channels differ. [ICO-02][ICO-04][KL-FORMS-01]
• Use an unchecked affirmative control when the selected jurisdiction route requires consent, keep optional marketing separate from terms or resource delivery, and retain the exact copy shown with its policy/form version. [ICO-CONSENT-01][ICO-02][MC-GDPR-01]
• Collect only fields that support the stated signup, preference, routing, or personalization purpose, and explain why optional information is requested. [ICO-CONSENT-01][MC-GDPR-01]
• Use confirmation or double opt-in when stronger address ownership and intent verification is appropriate; do not treat an unconfirmed grant as subscribed. [KL-DOI-01][MC-DOI-01]

Double opt-in and welcome handoff

• Choose single or double opt-in from the applicable jurisdiction route, risk, list-quality needs, and documented business policy; double opt-in is a strong verification practice, not a universal legal requirement. [MC-DOI-01][KL-DOI-01][ICO-01]
• Prefer double opt-in when fake signups, mistyped addresses, weak source assurance, or proof-of-intent risk outweigh the extra confirmation step. [KL-DOI-01][MC-DOI-01]
• For double opt-in, key PENDING_CONFIRMATION to the contact, list, channel, and purpose after form submission; send only the confirmation message for that pending grant and move that grant to SUBSCRIBED only after confirmation. An expired or absent confirmation keeps marketing under that grant ineligible without suppressing unrelated eligible service or a separately verified permission. [MC-DOI-01][KL-DOI-01]
• Keep confirmation copy limited to the requested verification, identify the sender and requested channel, and provide a clear confirm action without unrelated promotion. [MC-DOI-01][FTC-01]
• Hand a SUBSCRIBED grant and its source, statement version, confirmation timestamp, jurisdiction, list, channel, purpose, and preferences to 02-welcome-onboarding; trigger welcome only for the same list, channel, and purpose, never from the matching PENDING_CONFIRMATION grant. [KL-DOI-01][KL-WELCOME-01][ICO-CONSENT-01]