Email deliverability is the measure of how successfully your emails reach recipients' inboxes rather than spam folders or getting blocked entirely. In 2026, with increasingly sophisticated spam filters from Gmail, Microsoft, and Yahoo, deliverability requires active management.
This guide covers everything you need to know to maximize your inbox placement rate.
Four pillars determine whether your email reaches the inbox:
Your sender reputation is a score assigned by ISPs based on your sending history. Think of it like a credit score for email.
| Factor | Impact | Threshold |
|---|---|---|
| Bounce rate | High | Keep below 2% |
| Spam complaints | Very High | Keep below 0.1% |
| Spam trap hits | Critical | Must be zero |
| Sending to inactive addresses | Medium | Remove after 90 days of no engagement |
| Sudden volume spikes | Medium | Ramp up gradually |
Email authentication tells ISPs that your emails are legitimately from you, not spoofed by bad actors.
SPF specifies which servers are allowed to send email for your domain.
v=spf1 include:_spf.google.com include:sendgrid.net ~all
Common mistakes:
+all instead of ~all or -allDKIM adds a cryptographic signature to your emails, proving they haven't been tampered with in transit.
Most ESPs (SendGrid, Mailchimp, Amazon SES) provide DKIM setup guides. You'll add a CNAME or TXT record to your DNS.
DMARC ties SPF and DKIM together and tells ISPs what to do with emails that fail authentication.
Start with a monitoring policy:
v=DMARC1; p=none; rua=mailto:[email protected]; pct=100
Once you're confident in your setup, move to p=quarantine and eventually p=reject.
BIMI displays your brand logo next to your emails in supported inboxes (Gmail, Apple Mail, Yahoo). It requires a verified DMARC policy with p=quarantine or p=reject.
This is where most senders fail — and where email verification makes the biggest impact.
Email addresses decay at approximately 22% per year:
| Address Type | Action |
|---|---|
| Hard bounces | Remove immediately |
| Soft bounces (3+ times) | Remove |
| Disposable emails | Remove |
| Role-based (info@, admin@) | Consider removing or segregating |
| Catch-all domains | Flag for monitoring |
| No engagement (90+ days) | Re-engagement campaign, then remove |
| Spam trap addresses | Remove immediately |
This process takes minutes for lists up to 100,000 addresses and typically removes 10-25% of addresses.
Since February 2024, Gmail and Yahoo enforce strict requirements for bulk senders (5,000+ emails/day):
Non-compliance results in throttling, deferrals, or outright blocking.
Email deliverability isn't a one-time setup — it's an ongoing practice. Start with the fundamentals: authenticate your domain, verify your email list, and monitor your sending reputation.
MailRook can help with the list hygiene pillar. Start with 100 free email verification checks per day — no credit card required.
Your emails are only as good as your ability to deliver them. A 99% open rate means nothing if only 50% of your emails reach the inbox.
Start with 100 free email checks per day. No credit card required.
Get Started Free