What is deliverability?
Nicklas Segatz Mortensen · Growth Hacker · Fractional CMO · Meta Ads Nerd · 8 July 2026 · 4 min.
Definition
Deliverability is the share of your sent emails that actually land in the recipient's inbox rather than in spam or getting rejected entirely.
Also called: Deliverability, Inbox placement, Email deliverability
Sådan virker det
Deliverability er, hvor stor en del af dine mails der reelt når indbakken frem for spam. Den styres af afsender-reputation, som bygges gennem engagement og ødelægges af at sende til uengagerede eller døde adresser. Uden deliverability er alt andet ligegyldigt.
01The foundation under all email work
The best flow logic and the sharpest subject lines are pointless if the email lands in spam. Deliverability determines whether your work even gets seen. It's governed by your sender reputation, which is built over time through engagement — opens, clicks, purchases — and eroded by sending to unengaged or dead addresses.
Deliverability is therefore as much hygiene as it is technique. Proper domain authentication (SPF, DKIM, DMARC), a dedicated sending subdomain, double opt-in, ongoing list hygiene and a sunset flow all work together to keep you in the inbox. Neglect them, and the list slowly fades out of sight — without you necessarily noticing why.
Frequently asked questions
How do I improve my deliverability?+
Authenticate your domain (SPF, DKIM, DMARC), send from a dedicated subdomain, use double opt-in, keep the list clean with a sunset flow, and send mainly to the engaged. Engagement builds reputation, which builds inbox placement.
How do I know if I have a deliverability problem?+
Falling open rates despite a good history, emails landing in the spam folder on testing, or sudden swings after large sends to the unengaged. Klaviyo's and inbox providers' tools can help diagnose it.
Related terms
Glossary
What are SPF, DKIM and DMARC?
SPF, DKIM and DMARC are email authentication standards that let the recipient's mail server verify that an email really was sent from the domain it claims — and therefore isn't spoofed.
Read the entry →Glossary
What is a sunset flow?
A sunset flow gradually steps profiles that haven't engaged over a longer period down and eventually out of active sending — to protect your sender reputation.
Read the entry →Glossary
What is double opt-in?
Double opt-in is a sign-up method where a new contact must confirm their subscription via a link in an email before they're added to your active list.
Read the entry →Deliverability, flows and list hygiene — we build them into the Klaviyo setup.
See Klaviyo & Email →
Nicklas Segatz Mortensen
Growth Hacker · Fractional CMO · Meta Ads Nerd at Oaksmond
Growth hacker and fractional CMO with 10+ years' experience and hundreds of millions in managed ad spend behind him. Background from larger Danish and international scale-ups, and from the agency world.
Meet the team →