Substack · Substack Privacy Policy · View original document ↗

Contact Syncing and Address Book Data Collection

Medium severity Unique · 0 of 325 platforms
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Recent governance activity Substack recorded 6 documented changes in the last 30 days.
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This analysis describes what Substack's agreement states, permits, or reserves. It does not constitute a legal determination about enforceability. Regulatory applicability and practical outcomes may vary by jurisdiction, enforcement context, and individual circumstances. Read our methodology

ConductAtlas Analysis

Why it matters (compliance & governance perspective)

This clause establishes the operational mechanics for a contact discovery feature that requires dual opt-in from both the user syncing their address book and the user being identified as a contact. The use of hashed storage limits the form in which this contact data is retained in Substack's systems.

Recent Activity

This document changed recently

Medium May 5, 2026

Substack now discloses that it shares account identifiers, such as email addresses and usernames, with trusted industry child safety organizations to detect and prevent online child sexual exploitation and abuse. The policy also establishes that Substack will respond to privacy rights requests within one month, or up to three months for complex requests, providing more certainty about response timelines. Additionally, the policy clarifies that direct message recipients may retain messages even if you request deletion or delete your account, which is now explicitly stated rather than implied.

View change record →
Medium Apr 19, 2026

The updated policy no longer commits to responding to privacy rights requests within one month or within three months for complex requests. This removes a procedural timeline that previously bound Substack's response obligations. Additionally, the explicit disclosure that Substack shares account identifiers with child safety consortia to detect online child sexual exploitation has been removed from the policy, though the practice itself is not stated to have ended. The direct message retention language is now framed more directly: recipients may retain messages even if you request deletion or close your account.

View change record →

Consumer impact (what this means for users)

Users who enable contact syncing authorize Substack to process their address book data and share their profile information with other opted-in users who list them as contacts. Users who do not enable contact syncing are not subject to address book collection, though their profile information may still be shared if another user has enabled the feature and identified them as a contact.

How other platforms handle this

Roblox Medium

Your use of the Services is also governed by our Privacy Policy, which is incorporated into these Terms by reference. By using the Services, you consent to the data collection and use practices described in the Privacy Policy. Roblox collects information you provide directly, information collected a...

Best Buy Medium

We collect information about you in a variety of ways depending on how you interact with us and our products and services. This includes information you provide directly, information we collect automatically when you use our services, and information we receive from third parties. We may collect ide...

Tabnine Medium

Tabnine may collect and use technical data and related information, including but not limited to technical information about your device, system and application software, and usage data regarding your use of the Services (including code completion statistics and plugin interaction data), to facilita...

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▸ View Original Clause Language DOCUMENT RECORD
"
We may also collect information about you when one of our users syncs their address book information with our app for contact syncing purposes. This information collection is strictly limited to email addresses and phone numbers, and any information collected in this manner is securely stored only as hashed values. ... to facilitate contact syncing between users who opt in to our app's contact syncing functionality; ... If you opt into contact syncing through our app, your profile information will be shared with any user who has (i) also opted into contact syncing, and who (ii) identified you as a contact.

— Excerpt from Substack's Substack Privacy Policy

Applicable regulations

CCPA/CPRA
California, USA
Connecticut Data Privacy Act Amendments
US-CT
CAN-SPAM
United States Federal
ePrivacy Directive
European Union
FTC Act Section 5
United States Federal
GDPR
European Union
Indiana Consumer Data Protection Act
US-IN
Kentucky Consumer Data Protection Act
US-KY
UK GDPR
United Kingdom
Universal Opt-Out Mechanism Expansion 2026
US

Provision details

Document information
Document
Substack Privacy Policy
Entity
Substack
Document last updated
May 5, 2026
Tracking information
First tracked
May 11, 2026
Last verified
May 11, 2026
Record ID
CA-P-006890
Document ID
CA-D-00178
Evidence Provenance
Source URL
Wayback Machine
Content hash (SHA-256)
69d115f06fc1e4f75cab0566ca01b279d70be9b2c99c4c197c67a2922d1622b7
Analysis generated
May 11, 2026 04:34 UTC
Methodology
Evidence
✓ Snapshot stored   ✓ Hash verified
Citation Record
Entity: Substack
Document: Substack Privacy Policy
Record ID: CA-P-006890
Captured: 2026-05-11 04:34:06 UTC
SHA-256: 69d115f06fc1e4f7…
URL: https://conductatlas.com/platform/substack/substack-privacy-policy/contact-syncing-and-address-book-data-collection/
Accessed: May 20, 2026
Permanent archival reference. Stable identifier suitable for legal filings, compliance documentation, and research citation.
Classification
Severity
Medium
Categories

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Frequently Asked Questions

What does Substack's Contact Syncing and Address Book Data Collection clause do?

This clause establishes the operational mechanics for a contact discovery feature that requires dual opt-in from both the user syncing their address book and the user being identified as a contact. The use of hashed storage limits the form in which this contact data is retained in Substack's systems.

How does this clause affect you?

Users who enable contact syncing authorize Substack to process their address book data and share their profile information with other opted-in users who list them as contacts. Users who do not enable contact syncing are not subject to address book collection, though their profile information may still be shared if another user has enabled the feature and identified them as …

Is ConductAtlas affiliated with Substack?

No. ConductAtlas is an independent monitoring service. We are not affiliated with, endorsed by, or sponsored by Substack.