“It landed in spam” are four words no email marketer wants to hear.
Studies show that while the average email delivery rate is around 98%, only about 78% of those emails actually reach the inbox. That 20% loss doesn’t just mean fewer opens. It means wasted ad spend, lower conversions, and a sender reputation that only gets worse.
Why?
Because mailbox providers judge more than your ability to send. Engagement, spam complaints, and authentication all determine whether your emails reach the intended recipient.
So how can you raise your email deliverability rate and keep your email campaigns out of the spam folder?
Keep reading to learn what deliverability rate really means, how to calculate it, and which small changes can dramatically improve your inbox placement this week.
Key takeaways
- Email deliverability rate is what really matters. Not how many emails you send, but how many land in inbox. Authentication (SPF, DKIM, DMARC), list quality, and engagement determine that number.
- Trust over volume. The more your audience opens, clicks, and replies, the better your reputation. Make sure you have a clean list, a predictable sending schedule, and genuine content.
What “email deliverability rate” means (and what it’s not)
People sometimes confuse delivery rate with deliverability rate, but they’re not the same thing.
Your delivery rate is based on how many messages make it to a server without bouncing. If you send 10,000 emails and 9,800 don’t bounce, your delivery rate is 98%.
Your email deliverability rate shows how many of those 9,800 emails land in the inbox instead of spam. You can technically “deliver” an email that no one ever sees, and that’s the number that really matters.
According to Validity’s 2025 benchmark report, the average email deliverability rate across industries is around 78–83%, while top performers go up to 90% or higher. Anything below 80% usually points to a poor sender reputation, poor list quality, or both.
All major mailbox providers determine inbox placement by tracking behavior (opens, clicks, replies), spam complaint rate, authentication, and the overall list hygiene. Sometimes, just one campaign with too many complaints or bounces can drag your reputation down for weeks.
Quick math:
- Delivery rate = (Delivered / Sent) x 100
- Inbox placement rate = (Inbox / Delivered) x 100
So, if you sent 10,000 emails, 9,800 were delivered, and 7,800 landed in the inbox, your deliverability rate is 79.5% and that’s the number you want to watch out for.
Email authentication basics
Before worrying about engagement or what color palette your next email should use, you need something far more basic: proof that you are who you say you are. That proof comes from three authentication standards: SPF, DKIM, and DMARC.
- SPF (Sender Policy Framework) tells email service providers which servers are allowed to send emails for your domain. If your email comes from a server not on that list, Gmail or Outlook will treat it with suspicion.
- DKIM (DomainKeys Identified Mail) adds a digital signature to every message. It lets providers confirm the message wasn’t changed on the way and ties it to your domain.
- DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together. It tells mailbox providers what to do when SPF/DKIM fail (none/quarantine/reject) and sends you reports.
A minimum viable setup today looks like this:
- An SPF record that explicitly lists your sending service.
- A DKIM key that matches the sender domain.
- A DMARC policy (start with “none”) so you can collect reports before enforcing stricter rules.
Under 47% of domains these days have a valid DMARC record, which is quite disappointing. And while some marketers jump to new sending infrastructure or “better” email platforms, that alone doesn’t guarantee inbox access if these authentication standards haven’t been met.
How mailbox providers measure your reputation
Once authentication is in place, reputation decides whether your emails stay welcome or start getting filtered. Every major provider tracks your behavior over time and judges based on patterns it sees.
The most important parameters are:
- Spam complaints: The biggest one. Gmail’s informal “red line” is about 0.1% which is roughly one spam report per thousand emails. Anything above that leans toward the spambox territory.
- Bounce rates: Keep total bounces (hard + soft) under 2%. High bounces usually mean sloppy list hygiene.
- Engagement: Opens, clicks, replies, and even how quickly users delete your mail. High engagement means your messages are wanted; zero engagement makes you look like an eloquent spammer.
- Send consistency: Big, sudden jumps in volume are an instant trust breaker. Going from 1,000 to 10,000 overnight looks like a hijacked account.
- Spam traps and recycled addresses: Sending to these addresses tells spam filters your data is stale or purchased. Sending to one might be fine, but doing it repeatedly can blacklist your domain.
Over time, mailbox algorithms start associating your domain and IP with a “sender reputation score.” If your engagement stays high, they’ll route you to the recipient’s inbox. If complaints or bounces go up, you’ll eventually slide toward Promotions or Spam without any warning.
New IP warm-up best practices
When you start sending from a new domain or infrastructure, your reputation starts at zero. Your job is to prove you won’t spam people if ESPs grant you access to their mailboxes.
A simple warm-up plan looks like this:
- Day 1–3: Send a few hundred transactional or internal emails (password resets, notifications).
- Day 4–7: Gradually double your send volume each day if metrics show you’re on track.
- Week 2–3: Add small marketing batches or newsletters. Keep total sends under a few thousand per day.
- After Week 3: Scale slowly until you reach your target daily volume.
You can also use our free warm-up planner on the website to keep things on track.
And if you need expert help, check out InboxAlly to actively improve engagement and keep your deliverability in top shape. It’s one of the best ways to teach mailbox providers that you are a trustworthy sender, which is exactly what keeps your placement where you want it to be.
List quality: the make or break of your deliverability
Most deliverability issues come from your list, plain and simple. Even one neglected import or a batch of old leads can poison your sender reputation. When ESPs see you emailing people who never open or repeatedly bounce, they treat you as suspicious.
Here’s what hurts most:
- Inactive or invalid email addresses: High bounce rates mean bad data. Providers expect you to remove inactive contacts after 6–12 months of no engagement.
- Role accounts: Addresses like info@, sales@, or support@ rarely belong to one person. They generate low engagement and high complaint rates.
- Old imports: Lists from CRMs or past events usually include abandoned email accounts and spam traps. Uploading them directly is one of the quickest ways to ruin your reputation.
Double opt-in vs. single opt-in
A single opt-in adds anyone who fills out your form. A double opt-in adds only those who confirm via a verification email. Double opt-in means slower list building, but it also makes sure that every subscriber is an engaged, real person, which is why it’s the best practice for newsletters, B2B, or anything that needs long-term trust. Single opt-in is fine for low-risk transactional or gated-content lists, but it needs stricter cleanup.
Practical hygiene:
- Define a decay window. For example, remove or suppress contacts who haven’t opened in 90 days or so.
- Run re-engagement email marketing campaigns once before removal. If they don’t respond, stop sending.
- Track engagement recency instead of total volume. Sending less to more active users improves primary inbox rates dramatically.
Checklist: lists to remove immediately
- Contest or giveaway signups.
- Scraped or third-party contacts.
- Purchased “verified” databases.
- Imports older than a year with no activity.
The cleaner your list, the more likely your marketing emails will get to people who want to see what you have to offer.
Testing and monitoring
Email deliverability doesn’t have to be a mystery. It’s measurable if you track it properly.
Do not wait for open rates to crash before investigating. Monitor a few simple things every week:
- Delivery rate
- Inbox placement tests
- Complaint rate
- Bounce types
- Average read time
- Domain-level health.
There are plenty of email deliverability tools, both paid and free, that make this easy to track, so make sure you do it regularly.
Seed tests, which means sending to test inboxes across email providers, show you how your emails behave in different environments. Real-audience panels add to that by showing you what actual subscribers see, open, and click. Use both. One gives you lab results; the other shows real-world behavior.
Set up alerts for sudden complaint spikes or authentication failures. When you get a broken DKIM record or an increase in spam reports, you can essentially undo months of good history, so make sure you catch it ASAP.
Quick fixes vs. long-term gains
Some problems in deliverability can be fixed before the week’s over. Others need time, repetition, and proof that you’re not a one-hit wonder. The difference between the two is what separates stable inboxing from constant firefighting.
So how do you do it?
Start with the low-hanging fixes. Clean out anyone who’s stopped engaging or keeps marking your campaigns as spam. If SPF, DKIM, or DMARC are broken, fix them yesterday. Remove addresses that have hard-bounced or haven’t engaged in a long time. And if your subject lines sound like bait (“Fwd:” or “Re:” when it’s not), rewrite them.
Then slow down… Make sure the people joining your list asked to be there in the first place, keep your sending schedule steady, and trim unresponsive contacts often. Inbox providers reward consistency more than reach.
And when you’re ready to play the long game, check out InboxAlly’s deliverability plans to turn those positive inbox interactions up a notch so your mail keeps landing in subscribers’ inboxes, even when you’re not looking.
Wrap it up!
And that’s it! So, summing up:
- Make sure SPF, DKIM, and DMARC are in place before sending anything.
- Remove inactive or unverified contacts regularly.
- Track more than open rates. Watch out for complaints, bounce types, and inbox placement.
- Avoid sudden volume spikes; build trust gradually.
- Don’t overthink your templates; authentic content wins over fancy design.
- Don’t be afraid to ask for help! Try InboxAlly if you need a quick and easy way to reach the inbox.
In the end, it’s quite simple: follow what you’ve learned here, and the inbox will keep welcoming your emails, no matter who you’re sending to.