To test email deliverability, send a sample message to a seed-list tool like Mail-Tester or GlockApps to see whether it lands in the inbox or spam. Then confirm your SPF, DKIM, and DMARC records pass, check your domain reputation in Google Postmaster Tools, and compare placement across Gmail, Outlook, and Yahoo.
Contents
- What's the Difference Between Email Delivery and Deliverability?
- How Do You Run an Inbox Placement Test?
- How Do You Check SPF, DKIM, and DMARC?
- How Do You Check Your Domain and Sender Reputation?
- What Are the Best Email Deliverability Test Tools?
- What Should You Do If Your Deliverability Test Fails?
What's the Difference Between Email Delivery and Deliverability?
These two terms sound the same. They're not.
Delivery means the receiving server accepted your email and it didn't bounce. Most senders see delivery rates of 95% or higher and assume everything's fine.
Deliverability is different. It measures whether your email actually reaches the primary inbox instead of the spam or promotions folder. That's the number that drives opens, clicks, and revenue.
So a "delivered" email can still be invisible. According to EmailTooltester's deliverability study, average inbox placement sits around 83–85%, which means roughly one in six delivered emails never reaches the inbox. Testing is how you find that gap before it costs you.
How Do You Run an Inbox Placement Test?
The fastest way to test email deliverability is a seed-list test. You send one email to a set of test addresses, and the tool reports where it landed across different providers.
Free tools like Mail-Tester give you a spam score out of 10 and flag content issues, broken authentication, and blocklist hits. Paid tools like GlockApps and Warmy go further, showing inbox-versus-spam placement provider by provider.
Run the test on a real campaign, not a plain "hello" email. Spam filters judge your subject line, links, and image-to-text ratio, so test the email you'd actually send.
How Do You Check SPF, DKIM, and DMARC?
Authentication proves to inbox providers that you are who you say you are. If it fails, your email gets filtered no matter how good the content is.
Three records do the work. SPF lists the servers allowed to send for your domain. DKIM adds a signature that proves the message wasn't tampered with. DMARC ties the two together and tells providers what to do with anything that fails.
A free tool like MXToolbox checks all three in seconds. Bulk senders now have to pass them: Google's sender guidelines require SPF, DKIM, and DMARC for anyone sending more than 5,000 emails a day.
How Do You Check Your Domain and Sender Reputation?
Your sender reputation is your email credit score. Providers use it to decide whether you reach the inbox, and a single bad send can drag it down.
Google Postmaster Tools is the place to start, and it's free. It shows your domain and IP reputation, spam complaint rate, and authentication results straight from Gmail's own data.
Also run a blocklist check (MXToolbox covers this too). If your domain or IP is listed, fix the root cause first, then request removal. Asking for delisting without fixing the problem just gets you relisted.
What Are the Best Email Deliverability Test Tools?
No single tool tests everything. Most marketers combine two or three: one for placement, one for authentication, and one for reputation.
| Tool | What it tests | Free? |
|---|---|---|
| Mail-Tester | Spam score, content issues, authentication, blocklists | Free (paid tiers available) |
| GlockApps | Inbox-vs-spam placement across major providers | Free trial, then paid |
| MXToolbox | SPF, DKIM, DMARC, and blocklist checks | Free |
| Google Postmaster Tools | Domain/IP reputation and complaint rate (Gmail) | Free |
Start with the free options. Mail-Tester plus Postmaster Tools will catch most problems before you ever pay for placement testing.
What Should You Do If Your Deliverability Test Fails?
A bad score isn't a dead end. It's a checklist.
Fix authentication first, since it's the most common culprit. Then suppress unengaged subscribers, slow your sending volume, and rebuild trust with the people who actually open your emails. Reputation recovery usually takes two to four weeks of disciplined sending.
The real fix is treating deliverability as ongoing maintenance, not a one-time test. A platform like Drip helps by handling authentication setup, dynamic segmentation, and list hygiene so your good senders aren't dragged down by dead weight. Retest after every major change, and you'll catch issues at a few hundred sends instead of a few hundred thousand.
