What is Email Deliverability?
Definition
Email deliverability is the ability of your emails to reach recipients' inboxes rather than their spam folders or being blocked outright. It depends on technical authentication, your sending reputation and how recipients engage with what you send.
Last updated 2026-10-18 · Flowmatix
How email deliverability works
Every time you send, mailbox providers like Gmail and Outlook decide where the message lands. They check three things. First, authentication: SPF, DKIM and DMARC records in your domain's DNS prove the message really came from you. Second, reputation: the history of your domain and sending servers, including complaints, bounces and spam-trap hits. Third, engagement: whether people open, reply, delete unread or mark you as spam.
Google publishes specific rules in its email sender guidelines. All senders to personal Gmail accounts need SPF or DKIM and should keep the spam rate reported in Postmaster Tools below 0.3%. Senders of more than 5,000 messages a day must set up SPF, DKIM and DMARC, and marketing messages must support one-click unsubscribe with a visible unsubscribe link.
Example: a fitness studio switches newsletter platforms but never adds the new provider's DKIM record. Open rates fall by half overnight. Nothing about the content changed; the messages simply failed authentication and drifted into spam.
Why it matters for your business
Deliverability problems are silent. Your platform reports emails as "sent", yet customers never see them, so promotions underperform and invoices or booking confirmations go missing. Because reputation builds slowly and drops quickly, prevention is far cheaper than repair.
Good list practices help on every front. Sending only to people who opted in, as Canada's anti-spam law, CASL, generally requires, keeps complaints low. Our CASL guide for small businesses covers consent and list hygiene together.
Common mistakes
- Sending marketing from a free Gmail or Outlook address instead of your own authenticated domain.
- Importing an old or purchased list, which brings bounces, spam traps and complaints.
- Hiding or slowing the unsubscribe process, which pushes people to the spam button instead.
- Blasting a large list after months of silence rather than sending regularly to engaged contacts.
- Mixing invoices and promotions on the same sending stream, so a marketing problem affects billing emails.
Frequently asked questions
How can I check my email deliverability?
Confirm SPF, DKIM and DMARC with a DNS checker, register your domain in Google Postmaster Tools to watch spam rate and reputation, and send test messages to accounts at several providers. Falling open rates at one provider are often the first warning sign.
Is deliverability the same as delivery rate?
No. Delivery rate counts messages a server accepted. Deliverability is about where accepted messages end up, inbox or spam, which most platforms cannot see directly.
Do small senders need DMARC?
Google requires DMARC for high-volume senders, but setting it up is worthwhile for any business domain because it also helps stop others from spoofing your address.
How Flowmatix can help
Our email marketing work puts this into practice for businesses in Toronto and around the world. Get a personalised quote in about 3 minutes.
Related terms
Ready to see what your project costs?
Answer a few questions and get a personalised plan, a comparison with typical market prices, and a clear next step. No obligation, no sales pressure.