Klaviyo Deliverability: Complete Guide

Quick Summary:

Deliverability -- actually reaching the inbox, not just avoiding bounces -- depends on domain authentication, list hygiene, and consistent engagement, not any single setting you configure once.

What Affects Deliverability?

Deliverability is about whether your emails genuinely reach the inbox rather than the spam folder, which is a different (and harder) problem than simply avoiding bounces. It depends on domain authentication, sending consistency, list hygiene, and ongoing engagement -- not a single setting, but an ongoing practice.

⚠️ Foundational Requirement

Proper SPF and DKIM domain authentication is not optional -- without it, mailbox providers have far less reason to trust mail from your domain, regardless of how good your content or list hygiene is otherwise.

How to Protect Deliverability

  1. Confirm SPF and DKIM are correctly configured for your sending domain.

  2. Scope regular campaign sends to your engaged-subscriber segment, not your full list.

  3. Regularly review and suppress genuinely unengaged, bounced, or invalid contacts.

  4. If migrating platforms or scaling volume significantly, warm up gradually rather than sending at full volume immediately.

  5. Monitor engagement trends over time, not just individual campaign performance.

A Real-World Example

A brand notices open rates declining over several months despite consistent content quality. Reviewing list composition reveals a large segment of contacts who haven't opened anything in over a year, still receiving every regular campaign. Excluding this unengaged segment from regular sends (while keeping a separate quarterly win-back attempt) restores healthier engagement rates and, over the following weeks, improves inbox placement for the remaining engaged list.

💡 Pro Tip

Treat deliverability as an ongoing practice, not a one-time setup task -- list hygiene and engagement-based sending need continuous attention as your list grows and customer behavior changes over time.

Frequently Asked Questions

What\'s the difference between deliverability and delivery rate?

Delivery rate simply measures whether an email wasn't bounced; deliverability is the broader concept of actually reaching the inbox (not spam folder) and being genuinely seen by recipients.

Does Klaviyo require domain authentication (SPF/DKIM)?

Yes, and it's strongly recommended -- proper domain authentication is foundational to good deliverability and is typically configured during initial account setup.

How does sending to unengaged contacts affect deliverability?

Consistently emailing unengaged contacts (low opens/clicks) signals to mailbox providers that your content isn't wanted, which can hurt inbox placement for your entire sending domain, not just that specific send.

Can a sudden spike in send volume hurt deliverability?

Yes, dramatically increasing volume without a gradual warm-up can trigger spam filtering, particularly on a newer sending domain without an established reputation.

What\'s list hygiene, and why does it matter for deliverability?

List hygiene means regularly removing or suppressing unengaged, bounced, or invalid contacts -- a cleaner list with genuinely engaged recipients protects sender reputation better than a large but stale one.

Does Klaviyo provide any built-in deliverability monitoring?

Yes, Klaviyo provides deliverability-related reporting and guidance, though ongoing monitoring and list hygiene practices remain the sender's responsibility.

Can poor SMS deliverability affect email deliverability, or are they independent?

SMS and email deliverability are generally governed by separate infrastructure and reputation systems -- problems in one channel don't directly affect the other.

What\'s a healthy engagement rate to maintain for good deliverability?

This varies by industry, but consistently low open rates (well below industry benchmarks) are a warning sign worth investigating rather than a number to ignore.

Should I suppress unengaged subscribers entirely, or just exclude them from regular sends?

Most deliverability-conscious strategies exclude unengaged contacts from regular promotional sends while keeping them on the list for occasional win-back attempts, rather than deleting them outright.

Can migrating to Klaviyo from another platform affect deliverability initially?

Yes, a new sending domain or platform change can require a warm-up period, gradually increasing volume, to establish sender reputation with mailbox providers.