January is the best month of the year to rebuild an email and SMS program. Holiday sends are done, the list is at its biggest and least engaged, and every flow has just been stress-tested by peak traffic. This guide covers the revamp in the order we run it: list hygiene, deliverability, flow audit, segmentation, then SMS compliance.
It doesn't repeat the basics we've covered elsewhere. For subject lines and calls to action, see quick tips to improve your click-through rate. For opt-out problems, see how to reduce your unsubscribe rate. For signup forms, see growing your list with A/B testing.
When should you start an email and SMS revamp?
Start the audit in the first two weeks of January, once holiday returns and post-purchase flows have run their course. Clean the list and fix deliverability before February, rebuild flows and segments through Q1, and have the new program running before spring promotions and well before planning for Black Friday 2027 begins.
The holiday data is the reason to wait until January rather than start in December. You want to see which subscribers bought during Cyber Week, which ones only opened, and which ones went quiet through the heaviest send period of the year. That split drives every decision below.
If you're also planning site work for 2027, line the two up. A replatform changes your forms, tracking and event data, so read our 2027 replatform timeline before you rebuild flows that depend on them. Smaller site fixes belong on the 2027 site optimization roadmap.
How do you clean your email list after the holidays?
Split the list by engagement and purchase history, then suppress or sunset the subscribers who haven't clicked or bought in a set window, often 90 to 180 days depending on how often you send and how often customers buy. Mailing people who ignore you raises complaint rates, which hurts delivery to the people who do read.
Use clicks and orders, not opens, as the engagement signal. Apple's Mail Privacy Protection downloads remote content in the background when a message arrives, not when it's read, so an "open" from an Apple Mail user may not mean anyone looked.
A practical cleanup order:
- Remove the obvious. Hard bounces, role addresses that never engage, and spam traps your platform flags.
- Build four groups. Engaged buyers, engaged non-buyers, lapsed buyers and never-engaged subscribers.
- Run a sunset flow. Send the never-engaged group a short win-back or "do you still want these" sequence, then suppress anyone who doesn't click.
- Protect lapsed buyers. Customers who bought once and went quiet are a win-back segment, not a deletion list. Keep them out of daily campaigns and give them their own flow.
Expect the list to shrink. That's the point. A smaller list that clicks earns better inbox placement than a big one that doesn't.
What are the 2026 email deliverability rules?
Gmail, Yahoo and Microsoft Outlook all require bulk senders to authenticate with SPF, DKIM and DMARC. Gmail and Yahoo also require one-click unsubscribe and a spam complaint rate below 0.3%. Gmail asks bulk senders to stay under 0.10%. Outlook has routed non-compliant high-volume mail to junk since May 2025.
The specifics, from each provider:
- Gmail: senders of 5,000 or more messages a day must set up SPF, DKIM and DMARC (a policy of none is allowed), support one-click unsubscribe with a visible unsubscribe link, keep spam rates in Postmaster Tools below 0.10%, and avoid ever reaching 0.30% (Google).
- Yahoo: bulk senders must pass SPF and DKIM, publish a DMARC policy of at least p=none, support one-click unsubscribe under RFC 8058, honor unsubscribes within 2 days, and keep complaint rates below 0.3% (Yahoo Sender Hub).
- Outlook.com: domains sending more than 5,000 emails a day to Outlook.com, Hotmail.com and Live.com addresses must pass SPF, DKIM and DMARC. Since May 5, 2025, non-compliant mail goes to junk first and can eventually be rejected (Microsoft).
For the revamp, check three things. Your sending domain is your own branded domain, not your email platform's shared one. DMARC is published and passing for that domain. And the List-Unsubscribe headers are present on every marketing send. Check the raw headers of a real campaign rather than assuming your platform adds them.
Then watch Google Postmaster Tools weekly through January. The heaviest holiday sends are the most likely to push complaint rates up, and January is when you'll see the after-effects.
Which email flows should you audit first?
Audit the flows tied to buying intent first: welcome, browse abandonment, cart abandonment, checkout abandonment and post-purchase. They run every day without anyone watching, so they break quietly. Klaviyo's 2026 benchmarks report that flows generate nearly 41% of email revenue from 5.3% of sends.
For each flow, check:
- It still fires. Trigger events can stop arriving after a theme change, app swap or tracking update. Confirm recent entries in the flow's analytics.
- Codes and links work. Holiday discount codes expire. Collection URLs change. Click everything.
- Filters are right. A shopper who already bought shouldn't get the cart reminder. A subscriber on a subscription shouldn't get a "come back" offer for the product they already receive.
- Timing fits the product. A replenishment flow for a 30-day product shouldn't fire on day 60.
- The content is current. Holiday banners, old prices and discontinued products live longest in flows nobody reopened since last year.
Then look for flows you don't have. Brands with drops, subscriptions or seasonal lines usually need flows built around those events. When DYODE audited Echelon's Klaviyo account, the audit became an action plan led by subscription retention, and the build that followed added drop purchaser and notify-list flows, a reworked welcome flow and signup popup, and a profile cleanup.
How should you segment email and SMS for 2027?
Segment by what customers did, not only by what they told you: purchase history, product interest, lifecycle stage and engagement. Then use the segments to decide who doesn't get a send, as much as who does. A program built this way sends fewer, more relevant messages and protects deliverability at the same time.
Two habits make segmentation useful instead of decorative.
Read your own test results. For Grom, DYODE's first rounds of Klaviyo tests showed that most engaged subscribers had already bought and that midweek sends beat Saturday by a wide margin. The program shifted toward repeat buyers, with sizing reminders for kids who outgrew last season's fit. Your results will differ, which is why you test instead of copying a benchmark. Our post on 5 quick A/B tests covers the signup side.
Plan email and SMS with the rest of the calendar. For Spirit Jersey, paid social, paid search and email and SMS run as one funnel tied to product drops, licensed collaborations and seasonal moments. For Pair of Thieves, email and SMS were rebuilt around purchase behavior, product affinity and lifecycle stage. In both cases the segments came from the business calendar, not from the email tool's default list.
Small tactics belong in the same plan. One recommendation from DYODE's flow audit for Bentgo was re-sending a campaign 48 hours later to non-openers with a new subject line. Decide in advance which campaigns get a resend so it doesn't become a habit that inflates volume.
What SMS compliance rules matter in 2027?
Get prior express written consent for marketing texts, honor opt-outs sent by any reasonable means within 10 business days, and verify or register your sending number before the first send. One more FCC rule, which applies an opt-out to all of a sender's messages, is delayed to January 31, 2027. This is general information, not legal advice.
What's in effect and what's coming, as of November 2026:
- Opt-outs. Since April 11, 2025, FCC rules require honoring revocation through reasonable means, including keywords like stop, quit, cancel and unsubscribe, within 10 business days. One confirmation text that only confirms the opt-out, with no marketing, is allowed (FCC rule in the Federal Register).
- Revoke-all rule. The requirement to treat an opt-out from one type of message as applying to all future robocalls and robotexts on unrelated matters is now delayed to January 31, 2027 (FCC order DA 26-12). Plan for it in this revamp rather than after.
- One-to-one consent. The FCC's rule requiring consent to one seller at a time was vacated by the Eleventh Circuit on January 24, 2025 (the court's opinion). Consent language should still name your brand clearly.
- Sending numbers. Klaviyo recommends not sending from a toll-free number until it's verified, because carriers heavily filter unverified numbers. Verification takes about 2 to 5 business days and requires a live website (Klaviyo). Attentive and other SMS platforms have their own registration steps, so check yours before a new number goes live.
State laws, quiet hours and keyword requirements vary. Have counsel review your consent language and opt-out handling once a year, and January is a good time.
What should a revamped program look like by spring?
By March, you should have a smaller, cleaner list, authenticated sending that passes all three major mailbox providers, flows that fire and reflect current products, segments built from purchase behavior, and SMS consent records you can produce on request. Campaign volume should follow engagement, not the calendar.
From there, the work becomes routine: monthly reporting on revenue per recipient by flow and segment, a quarterly flow review, and a calendar that lines up email and SMS with site launches and promotions. Our Black Friday Cyber Monday checklist shows how that calendar pays off in November. For the channel and platform shifts worth planning around next year, see E-Commerce trends to plan for in 2027.
DYODE runs email and SMS programs on Klaviyo and Attentive for Shopify Plus and BigCommerce brands, and our E-Commerce audits cover email alongside paid media, analytics and the site. If you want a second read on your list, flows and deliverability before Q1 planning, start a conversation.
About DYODE. Founded in 2016 by former heads of E-Commerce at PacSun and Tilly’s. Shopify Premier Partner.
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