Deliverability
Updated
Email deliverability
Definition
Email deliverability is the ability of your emails to reach recipients' inboxes rather than bouncing or landing in spam. It differs from delivery rate, which only measures whether the receiving server accepted the message.
How it works
Every message passes three gates. First the receiving server accepts or rejects it (delivery). Then the mailbox provider's filters decide inbox, spam folder or a tab like Promotions (placement). Finally the recipient's behavior feeds back into how future mail is filtered.
Filters weigh authentication (SPF, DKIM, DMARC), the reputation of your domain and sending IPs, recipient engagement (opens, replies, deletes without reading, spam reports), list quality (bounces, spam traps) and content.
Inbox placement cannot be measured exactly from the sender side. Seed tests, Google Postmaster Tools and engagement trends give strong signals, but a delivered event only means the server accepted the mail.
Example
A high delivery rate does not prove inbox placement.
Why it matters
An email in the spam folder performs like an email that was never sent. Poor deliverability quietly cuts opens, clicks and revenue from every campaign.
Reputation builds slowly and drops fast. A single campaign to an old, unconfirmed list can raise complaints and bounces enough to hurt every later send from the same domain.
Benchmarks
- Authenticate every sending domain with SPF, DKIM and DMARC, aligned with your From address.
- Send only to people who opted in, and make unsubscribing one click.
- Remove hard bounces immediately and sunset subscribers who stopped engaging.
- Keep volume consistent, and warm up new domains and IPs gradually.
| Signal | Healthy | Act now |
|---|---|---|
| Spam complaint rate (Gmail Postmaster) | Below 0.1% | 0.3% or higher |
| Hard bounce rate per send | Below 2% | 5% or higher |
| Authentication | SPF, DKIM and DMARC aligned | Any missing for bulk mail |
| Unsubscribe | One-click (RFC 8058) | Hidden or multi-step |
How Lumail handles email deliverability
Lumail checks domain authentication during onboarding. New accounts can build and test, and sending to your audience unlocks automatically when your SPF, DKIM, MAIL FROM and DMARC records verify.
After that, a sender score (0-100) built from the last 30 days of bounces, complaints, opens and clicks keeps sending unlocked. Settings, Deliverability shows sender health, outcome metrics and a fix for every alert, and permanent bounces and complainers are suppressed automatically.
Check a real message with the free mail tester or the spam tester.
Frequently asked questions
What is the difference between delivery rate and deliverability?
Delivery rate is the share of sent emails the receiving server accepted. Deliverability is whether those accepted emails reach the inbox. You can have 99% delivery and still land mostly in spam.
How do I check my email deliverability?
Send a real message to a mail tester to verify authentication and content, watch your bounce and complaint rates per send, and register your domain in Google Postmaster Tools to see Gmail's spam rate.
Does the Promotions tab hurt deliverability?
Promotions is still the inbox, not spam. Gmail sorts by content type. Engagement from subscribers who want your mail matters far more than which tab it lands in.
Related terms, tools and docs
- DeliverabilitySender reputationSender reputation is the trust score mailbox providers assign to your sending domain and IP addresses, based on how recipients and their systems react to your mail.
- MetricsSpam complaint rateSpam complaint rate is the percentage of delivered emails that recipients reported as spam.
- MetricsBounce rateEmail bounce rate is the percentage of sent emails that the receiving server rejected as undeliverable.
- AuthenticationDMARCDMARC is a DNS TXT record at _dmarc.yourdomain.com that tells receivers what to do with mail that claims to be from your domain but fails authentication.
- Free toolFree mail testerSend a real email and get an SPF, DKIM, DMARC and content report.
- Free toolFree spam testerCheck an email for the patterns that push mail to spam.
- DocsDeliverability guideEvery deliverability alert Lumail raises and its fix.
- DocsSender healthHow Lumail measures sending health and authentication.
- DocsAccount verificationHow sending unlocks when your domain verifies.
Browse every definition in the email marketing glossary.
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