Unsubscribe links, platform by platform
Every commercial message has to give the reader a way out, and every sending platform hides that mechanism somewhere different. This category is one page per platform: where the unsubscribe tag lives in that editor, the exact merge field or header the platform expects, and what it does with the address once someone clicks. The guides cover the largest marketing platforms, the transactional relays, the CRM suites and the self-hosted scripts, each with the wording that platform actually uses in its own interface.
Two mechanisms, two audiences
The visible footer link answers to the law. CAN-SPAM asks for an opt-out that keeps working for at least 30 days after the send and is honored within 10 business days, with no fee and no information required beyond the address. GDPR and CASL frame the same act as withdrawing consent, which has to be as easy as giving it was.
The header answers to the mailbox providers. Since February 2024, Gmail and Yahoo require a one-click List-Unsubscribe-Post on any sender above 5,000 recipients a day to their domains, and Microsoft aligned in May 2025. A footer link with no header satisfies the statute and still loses placement, which is why every guide in this category covers both.
Start here
How the link is built
Merge tags, hosted preference pages, and the difference between a tag your platform expands and a URL you host yourself.
One-click for bulk senders
The header pair receivers parse, the POST body they send back, and the endpoint you have to answer with.
What each jurisdiction asks
Deadlines, wording and proof requirements differ by country, and the strictest rule applies to a mixed list.
Guides by platform family
The setup differs less by brand than by what the tool is for. A marketing platform manages the list and owns the opt-out; a relay sends what your application hands it and expects the header to come from your code. Pick the family that matches your stack.
Marketing platforms
The list lives in the tool, the opt-out is a merge tag, and the suppression is automatic. The work is choosing between the default page and a preference centre.
Mailchimp, Constant Contact, Klaviyo, Brevo, MailerLite, ActiveCampaign, Kit
Relays and transactional APIs
Your application decides what gets sent, so the header and the suppression write are yours to implement. Most of these expose an unsubscribe group or a substitution tag to do it for you.
CRM and automation suites
Opt-out state is a field on a contact record shared with sales, so the question is which subscription types a single click clears and which it leaves running.
HubSpot, Salesforce Marketing Cloud, Adobe Marketo, Keap, Ortto
Cold outreach tools
Sequences sent from a personal mailbox still count as commercial mail. These guides cover the opt-out snippet, the sequence-level stop, and the shared blocklist that keeps it from firing twice.
What a complete implementation includes
Four pieces have to be in place, and a platform guide will only ever hand you the first two. The visible link belongs in the footer, close to the sender identity and the postal address, where readers look for it rather than in a grey line under the tracking pixel. The anatomy of a working footer covers what else has to sit there.
The headers come next. The URL form was standardised in RFC 2369 and the one-click extension in RFC 8058; the receiver posts to your endpoint and expects a success response, not a confirmation page. Then the write: the address has to land on a list that every future send consults, which is the point of a durable suppression list rather than a per-campaign exclusion.
The fourth piece is measurement. Complaint volume and the spam rate that mailbox providers judge you on are visible in Google Postmaster Tools, and the thresholds each provider publishes are collected in the guide to bulk sender rules at Gmail, Yahoo and Microsoft.
When the opt-out is not the problem
A rising complaint rate with a working link usually means the reader could not find it, or never expected the mail at all. Complaints arrive through the provider rather than your footer, and reading them requires feedback loop enrolment and ARF parsing. Consent quality upstream is the other half of the same problem, which is where double opt-in and its deliverability effect belongs.
If messages are failing before anyone sees the footer, the answer is elsewhere on the site: undeliverable addresses are covered in bounce handling, starting with the hard and soft distinction, and the exact wording a receiver returned is catalogued in the SMTP code reference. The standards texts behind all of it sit in the RFC library.
