How do I set up custom domain authentication in Klaviyo?

Klaviyo Settings → Email → Domains → Add Sending Domain. Enter your domain. Klaviyo provides DKIM CNAME records and an SPF include. Add these to your DNS. Verify in Klaviyo. Until you do this, Klaviyo sends with their default DKIM domain, which hurts DMARC alignment.

What is Klaviyo Smart Sending?

Smart Sending prevents sending multiple emails to the same contact within a configurable timeframe (default: 16 hours). It suppresses campaign sends to contacts who recently received another email. Enable it in Settings → Email → Smart Sending. It's off by default on some accounts.

Should I suppress unsubscribed profiles in Klaviyo?

Yes, and also delete bounced/invalid profiles. Since February 2025, Klaviyo charges for ALL profiles including unsubscribed. A 100K profile list with 25K unsubscribed costs you for 100K. Regularly suppress/delete profiles you can't email.

How do I create engagement segments in Klaviyo?

Create a segment with conditions: 'Opened Email at least once in the last 90 days' OR 'Clicked Email at least once in the last 90 days' OR 'Placed Order in the last 180 days.' Send campaigns to this segment instead of your full list.

Does Klaviyo offer dedicated IPs?

Yes, for high-volume senders. Contact Klaviyo support to request. Recommended only if you send 100K+/month consistently. Below that, Klaviyo's managed shared pools are well-maintained and sufficient.

Klaviyo Deliverability Guide: Complete Optimization

Step 1: Custom Domain Authentication

This is the most important Klaviyo deliverability setting and most users skip it.

Without custom domain authentication, Klaviyo signs your email with their domain (not yours). DKIM passes for klaviyo.com but DMARC alignment fails because it doesn't match your From: domain.

Setup

Klaviyo → Account → Settings → Domains
Click Add Sending Domain
Enter your domain (e.g., yourbrand.com)
Klaviyo provides DNS records to add:

Record Type	Purpose
CNAME (×2)	DKIM signing with your domain
TXT	SPF include for Klaviyo

Add all records to your DNS
Back in Klaviyo → Verify

Custom Tracking Domain

Same page → Add a tracking domain (e.g., links.yourbrand.com):

CNAME: links.yourbrand.com → Klaviyo's tracking endpoint

DMARC (Manual)

Add to your DNS if not already:

_dmarc.yourbrand.com  TXT  v=DMARC1; p=none; rua=mailto:[email protected]

Step 2: Smart Sending

Enable in Settings → Email → Smart Sending.

Default: 16-hour window. If a contact received an email within the last 16 hours, they're suppressed from the next campaign.

Recommendation: Keep at 16 hours for most stores. Reduce to 8 hours only during high-send periods (BFCM) when you need maximum reach.

Smart Sending prevents the over-mailing that generates spam complaints and unsubscribes.

Step 3: Engagement-Based Segmentation

Create these segments for campaign targeting:

Engaged 30 Days (Primary Campaign Audience)

Opened Email at least 1 time in the last 30 days
OR Clicked Email at least 1 time in the last 30 days
OR Placed Order at least 1 time in the last 30 days

Engaged 90 Days (Extended Audience)

Opened Email at least 1 time in the last 90 days
OR Clicked Email at least 1 time in the last 90 days
OR Placed Order at least 1 time in the last 90 days

Unengaged 180+ Days (Sunset Candidates)

Has NOT Opened Email at least 1 time in the last 180 days
AND Has NOT Clicked Email at least 1 time in the last 180 days
AND Has NOT Placed Order at least 1 time in the last 180 days

Send campaigns to Engaged 30 or 90 Day segments. Run re-engagement flows for the 180+ day segment. Suppress after re-engagement fails.

Step 4: Profile Cleaning (Cost + Deliverability)

Since Feb 2025, Klaviyo charges for all profiles. Monthly cleaning saves money AND improves deliverability:

Delete hard bounced profiles (can't receive email)
Suppress profiles with no engagement 180+ days (hurting metrics)
Delete spam-complained profiles (should be auto-suppressed but verify)
Review suppression list — remove duplicates

Automated Cleaning Flow

Build a Klaviyo flow triggered by "No email activity for 180 days":

Send re-engagement email 1
Wait 3 days
Send re-engagement email 2
Wait 3 days
Check: opened either email? → Yes: keep. No: suppress profile.

Step 5: Monitor

Google Postmaster Tools: Set up for your sending domain. Check weekly for:

Domain reputation (should be Medium or High)
Spam rate (must be under 0.1%)
Authentication pass rates (should be ~100%)

Klaviyo Analytics: Email → Analytics tab:

Deliverability metrics per campaign
Bounce rates
Unsubscribe rates
Revenue attribution

Common Klaviyo Deliverability Mistakes

Not setting up custom domain authentication — the #1 issue
Sending to full list instead of engaged segments
Not enabling Smart Sending — over-mailing causes complaints
Keeping unsubscribed profiles — paying for contacts you can't email
No DMARC — authentication is incomplete
Skipping tracking domain — using Klaviyo's shared tracking domain

Practitioner note: Custom domain authentication is the first thing I configure for every Klaviyo client. Until it's set up, every email you send has a DMARC alignment issue that silently damages your deliverability. It takes 10 minutes. Do it now.

Practitioner note: After the February 2025 billing change, I run monthly profile cleanup for all Klaviyo clients. A typical 50K-profile account has 10-15K unsubscribed/bounced profiles that cost money every month. Cleaning saves $50-150/month in Klaviyo fees alone, plus improves engagement metrics.

If you need Klaviyo configured for optimal deliverability, schedule a consultation — I set up authentication, segmentation, and automated cleaning for Klaviyo stores.

Sources

v1.0 · March 2026