Guide
Email Deliverability, Explained
Deliverability is whether your email reaches the inbox, not just whether it was accepted. Here's what Gmail, Yahoo and Microsoft require, the numbers to stay under, and a checklist to fix it.
- SPF Pass
- DKIM Pass
- DMARC p=quarantine
- Spam complaint rate 0.04%
- Sends per mailbox 30 / day
- Blocklists Not listed
Inbox-ready ✓
Definitions
Delivery vs deliverability
Most dashboards report the first number. Your pipeline depends on the second.
| Metric | What it measures | What it misses |
|---|---|---|
| Delivery rate | Emails the receiving server accepted (didn't bounce). | Mail that was accepted and then put in spam. |
| Inbox placement | Emails that landed in the primary inbox or a tab. | Nothing: this is deliverability. |
| Bounce rate | Emails rejected outright (bad address, blocked sender). | Silent spam-foldering. |
| Spam complaint rate | Recipients who clicked “Report spam”. | People who ignore or delete you. |
Requirements
What Gmail, Yahoo and Outlook.com require from senders
Gmail and Yahoo began enforcing these rules in February 2024, and Microsoft followed for Outlook.com in May 2025. Bulk sender means more than 5,000 messages a day to that provider.
| Requirement | Applies to | Enforced by |
|---|---|---|
| SPF and DKIM authentication | All senders need at least one. Bulk senders need both. | Gmail, Yahoo, Outlook.com |
| DMARC record (p=none or stricter), aligned with SPF or DKIM | Bulk senders | Gmail, Yahoo, Outlook.com |
| Spam complaint rate under 0.3% | All senders (aim for under 0.1%) | Gmail, Yahoo |
| One-click unsubscribe (RFC 8058) | Bulk marketing and subscribed mail | Gmail, Yahoo |
| Valid reverse DNS (PTR) and TLS | All senders | Gmail |
Spam complaint rate thresholds
Spam reports ÷ emails delivered, as shown in Google Postmaster Tools.
- Healthy (under 0.1%)
- At risk (0.1%–0.3%)
- Filtered or rejected (0.3% and up)
- messages a day makes you a bulk sender
- 5,000+
- complaint rate Gmail tells senders never to reach
- 0.3%
- complaint rate to stay under
- 0.1%
- cold emails per mailbox per day we plan for
- 30
Factors
What decides where your email lands
| Factor | Why it matters | What to do |
|---|---|---|
| Authentication | Unauthenticated mail is treated as possibly spoofed. | Check SPF, DKIM, DMARC |
| Domain reputation | Providers score the domain in your From address. | Send cold email from separate domains, not your main one. |
| Mailbox history | New mailboxes with no history are watched closely. | Warm up gradually, or use pre-warmed mailboxes. |
| Volume per mailbox | Sudden or heavy sending looks like spam. | Keep to about 30/day per mailbox and add mailboxes to scale. |
| List quality | Bounces show you don't know your recipients. | Verify addresses before sending. |
| Engagement | Replies and “not spam” clicks build trust. | Target tightly and write for a reply, not a click. |
| Content | Link-heavy, image-heavy or salesy mail is filtered more. | Plain text, one link at most, no attachments in first touch. |
Warmup
Ramp new mailboxes up slowly
A brand-new mailbox that sends at full volume on day one looks exactly like a spammer. Increase volume week by week.
Cold emails per day from one new mailbox
Suggested ramp. Keep warmup running alongside; pre-warmed mailboxes can start at the final step.
| Week 1 | 5 |
|---|---|
| Week 2 | 10 |
| Week 3 | 20 |
| Week 4+ | 30 |
Skip the 3–4 week wait
Checklist
Email deliverability checklist
- Publish exactly one SPF record that includes your mailbox provider, under 10 DNS lookups.
- Turn on DKIM signing in Google Workspace or Microsoft 365 and publish the key.
- Publish a DMARC record with a reporting address, then tighten to quarantine and reject. Use the DMARC generator.
- Send cold email from separate domains, about 3 mailboxes per domain.
- Warm up new mailboxes, or start with pre-warmed ones.
- Keep each mailbox to about 30 cold emails a day.
- Verify every list before sending and remove hard bounces immediately.
- Write short, plain-text emails with one clear question.
- Watch your spam complaint rate in Google Postmaster Tools and stay under 0.1%.
- Monitor blocklists and DNS health, and run inbox placement tests before big campaigns.
Writing the emails themselves? Read the cold email guide for templates, subject lines and follow-ups.
Testing
How to test email deliverability
Test in layers, from DNS to the inbox. Each step catches problems the one before it can't see.
- Authentication: confirm SPF, DKIM and DMARC pass with the SPF checker and DMARC checker.
- Content: run your copy through a spam word checker and remove anything that reads like a promotion.
- Placement: send to seed accounts at Gmail, Outlook and Yahoo with an inbox placement test and see where each copy lands.
- Live monitoring: watch bounces, replies and your spam complaint rate in Google Postmaster Tools once campaigns are running.
Email deliverability score: what the numbers mean
| Score | Scale | What it measures | Use it for |
|---|---|---|---|
| Mail-tester | 0–10 | One test email: authentication, SpamAssassin content checks, blocklists. | Pre-send checks of a new template or domain |
| Sender Score (Validity) | 0–100 | The reputation of a sending IP. | Dedicated IPs you control |
| Inbox placement rate | % of seeds | How many test emails reached the inbox vs spam. | The closest thing to real deliverability |
| Spam complaint rate | % | Recipients who reported you, from Google Postmaster Tools. | Staying under Gmail's 0.3% limit |
Sending through Google or Microsoft? Read IP scores with care.
Outbound
Cold email deliverability
Cold email has a harder starting point: recipients never opted in, so there's no engagement history to protect you. Everything rests on infrastructure and restraint.
- Send from separate domains so your main company domain never carries the risk.
- Use real Google Workspace or Microsoft 365 mailboxes, about 30 cold emails each per day.
- Warm up new mailboxes, or start with pre-warmed ones, and keep warmup running.
- Verify every list. Hard bounces tell providers you don't know the people you're emailing.
- Write for a reply: short, plain text, no attachments, one question.
Already landing in spam? Start with why emails go to spam for a cause-by-cause fix list. Want someone else to run the setup and monitoring? Compare email deliverability services, or let Jetmail handle the domains, mailboxes and DNS with cold email infrastructure built for outbound.
Get a deliverability plan
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Or see pricing →Frequently asked questions
What is email deliverability?
Email deliverability is the share of your emails that land in the recipient's inbox rather than the spam folder or nowhere at all. It depends on authentication (SPF, DKIM, DMARC), sender reputation, sending volume, list quality and engagement.
What's the difference between delivery rate and deliverability?
Delivery rate only counts emails that weren't bounced, so spam-foldered mail still counts as delivered. Deliverability, or inbox placement, measures how many actually reached the inbox. A 99% delivery rate can still hide a serious spam problem.
How do I test email deliverability?
Check that SPF, DKIM and DMARC pass with a free checker, then run an inbox placement (seed) test that sends to test accounts at Gmail, Outlook and Yahoo and reports where each email landed. Jetmail's Deliverability Test does this in seconds.
What is a good email deliverability score?
There's no single industry score; each tool grades something different. Mail-tester scores one test email out of 10, where 10 is best. Validity's Sender Score rates a sending IP from 0 to 100. An inbox placement test reports the share of seed emails that reached the inbox. Track the same score over time rather than comparing across tools.
How is cold email deliverability different?
Cold recipients haven't asked to hear from you, so you can't lean on engagement history. You stay in the inbox through infrastructure instead: separate sending domains, authenticated Google or Microsoft mailboxes, about 30 emails per mailbox per day, verified lists and plain-text copy that invites a reply.
Why are my emails going to spam?
The usual causes are missing or broken authentication, a new domain sending too much too soon, high bounce or complaint rates, or a sending domain or IP on a blocklist. Start by checking your DNS records, then review volume per mailbox and list quality.
Does email warmup actually work?
Warmup builds a sending history slowly so mailbox providers learn to trust a new mailbox. It helps, but it can't fix broken authentication or a bad list. Pre-warmed mailboxes skip the waiting period by coming with that history already built.
What do email deliverability services do?
They set up and monitor the technical side: authentication records, blocklist monitoring, inbox placement testing and reputation tracking. Some, like Jetmail, also provide the mailboxes and domains themselves so the setup is right from day one.