Klaviyo deliverability problems are silent revenue killers. Your open rates look normal in your dashboard because Klaviyo only counts delivered emails, not ones that went to spam. If 15 percent of your sends are going to spam, your actual open rate from delivered emails might be 35 percent, but your real open rate from all sends is closer to 30 percent. Over a list of 50,000 subscribers, this difference represents thousands of missed conversions per month. Here is the complete checklist.
Authentication Checklist
SPF record: your domain's DNS must have an SPF record that authorises Klaviyo to send on your behalf. In Klaviyo go to Settings, Email, and then check the sending domain setup. The SPF record typically includes Klaviyo's mail servers (klaviyomail.com or your sending domain's CNAME records). Verify in MXToolbox that your SPF record is valid and includes Klaviyo's sending infrastructure.
DKIM: DomainKeys Identified Mail signs every email with a private key. Recipients verify with the public key published in your DNS. Klaviyo provides DKIM configuration in your sending domain settings. Verified DKIM is now required for sending to Gmail and Yahoo accounts at any volume. Unverified DKIM causes significant delivery problems with both providers.
DMARC: Domain-based Message Authentication, Reporting and Conformance. DMARC ties SPF and DKIM together and tells receiving servers what to do when authentication fails. Start with a p=none policy (monitoring mode) before moving to p=quarantine or p=reject. Without DMARC, your domain can be spoofed in phishing attacks, which damages your sender reputation even when you are not the sender.
List Health Checklist
Hard bounce rate below 2 percent: hard bounces indicate invalid email addresses. Above 2 percent signals a list quality problem. Check your Klaviyo list analytics monthly. Suppress all hard bounced profiles immediately, which Klaviyo does automatically.
Spam complaint rate below 0.1 percent: check in Klaviyo's deliverability dashboard. Above 0.1 percent requires immediate investigation. Common causes: sending to people who did not explicitly opt in, sending too frequently, or misleading subject lines.
Unsubscribe rate below 0.3 percent per send: above this threshold, your content-audience match is poor, or your send frequency is too high for your audience.
Engagement-based suppression: suppress profiles who have not opened any email in 180 days. Sending to chronically unengaged subscribers hurts your domain reputation for all your other sends. Clean suppression is a revenue-positive action, not a revenue loss.
Content Checklist
Text-to-image ratio: email with more than 60 percent image content and minimal text is flagged by spam filters. Every email should have substantial text content, not just images with text embedded in them. Alt text on all images: assistive technology and email clients that block images by default should still communicate the message.
Unsubscribe link visible and functional: all commercial emails require a clear, functional unsubscribe mechanism. Klaviyo includes this by default. Never customise or hide the unsubscribe link. A hard-to-find unsubscribe link generates spam complaints instead, which is worse for deliverability than losing the subscriber.