If your emails aren’t landing in inboxes, you’re not alone. Even seasoned marketers hit walls with deliverability. This guide is for anyone who’s frustrated by emails going missing, stuck in spam, or mangled in weird ways by different email clients. We’ll walk through how to actually use Litmus to troubleshoot and fix the stuff that matters—without the marketing fluff.
1. Know What Deliverability Really Means (and What It Doesn’t)
Let’s get clear on terms before you start poking around in tools. Email deliverability isn’t just about sending an email and hoping it arrives. It’s about ensuring your message:
- Lands in the recipient’s inbox (not spam, not promotions, not missing entirely)
- Shows up the way you intended (no broken formatting or missing images)
- Doesn’t get flagged as phishing or junk
What deliverability isn’t:
- It’s not just “did my ESP send it?”
- It’s not open rates (those are affected by lots of things)
- It’s not about fancy design tricks making up for bad sender reputation
The bottom line: If your emails aren’t being seen or look broken, you’ve got a deliverability problem.
2. Start With the Basics: Check Your Sender Reputation
Before you even open Litmus, check the simple stuff. Most deliverability issues come down to sender reputation—basically, whether inbox providers trust you.
What to check:
- Are you using a custom sending domain? Free Gmail or Outlook senders get filtered more.
- Are your authentication records set up? (SPF, DKIM, DMARC)
- Have you sent spam in the past, even by accident?
- Is your list clean, or are you hitting a bunch of dead addresses?
Pro tip: If you’re not sure about your authentication records, sites like MXToolbox can help you check. But Litmus’s built-in Spam Testing (more on this in a bit) makes it straightforward.
3. Run a Spam Test with Litmus
Here’s where Litmus actually saves you time. Their Spam Testing tool checks your email across a bunch of popular spam filters.
How to do it: 1. In Litmus, create a new test and send your email to the provided address. 2. Litmus automatically runs it through major spam filters (Gmail, Outlook, Barracuda, etc.). 3. Look for red flags—any failures or warnings.
What to look for: - Authentication errors: SPF, DKIM, or DMARC not passing? Fix these first. - Blacklists: If your sending IP or domain is blacklisted, that’s a big problem. - Spam filter triggers: Excessive use of spammy language, broken links, or missing unsubscribe links.
Honest take:
Litmus Spam Testing is great for catching obvious issues, but it’s not magic. It won’t fix a poor sender reputation overnight. If you’re repeatedly failing filters, you need to address your sending practices, not just tweak emails.
4. Preview Your Email Across Clients and Devices
You’d be surprised how many “deliverability” issues are just rendering problems. Your email might arrive, but if it looks broken, people ignore it—or worse, mark it as spam.
What works: - Litmus’s Email Previews show you how your message looks in dozens of email clients (Outlook, Apple Mail, Gmail, and more). - You can catch broken images, weird font issues, or layouts that fall apart on mobile.
How to use it: 1. In Litmus, upload your email or send a test. 2. Check the previews for popular clients your audience actually uses (don’t worry about the obscure ones unless you know you have users there). 3. Look for: - Broken images or missing alt text - Fonts that aren’t supported - Buttons or links that disappear or shift - Layouts that break on mobile
What to ignore:
Don’t get lost chasing pixel-perfect design in every single email client. Focus on the big ones—Gmail, Outlook, Apple Mail, mobile. Some edge-case quirks in old clients just aren’t worth the effort.
5. Test Your Links, Images, and Tracking
A lot of deliverability complaints start with “the link doesn’t work” or “my images never load.” That’s often because of:
- Broken URLs
- Blocked tracking domains
- Images hosted on slow or blacklisted servers
How Litmus helps: - The Link Checker finds busted links and images automatically. - It’ll flag any links that point to blacklisted domains (including tracking domains).
What to do: - Double-check every link Litmus flags. Don’t just trust your ESP’s editor. - Make sure image hosting isn’t from a free or sketchy source. - If your tracking domain keeps getting blocked, talk to your ESP about using a custom tracking domain.
Pro tip:
If you’re seeing images blocked a lot, consider using inline images (where appropriate), or make sure you have good alt text in place so your message still makes sense.
6. Use Litmus Analytics to Catch Real-World Issues
Sometimes, the problem isn’t obvious until real people start opening your emails.
What works: - Litmus’s Email Analytics shows you where your emails are being opened (devices, clients, even geolocation). - It can flag if a huge chunk of your audience is never seeing your email—which might mean you’re getting filtered to spam, or your design is totally broken for a key client.
How to use it: - Add the Litmus tracking pixel to your email (your ESP or developer can help if you’re not sure). - Check after every send for big drops in opens from key clients or regions. - If you see a sudden drop in Gmail opens, for example, you might be hitting spam there.
What doesn’t work:
Don’t obsess over minor changes in open rates—they can be affected by changes in Apple’s privacy policies, bot opens, and more. Look for big trends or sudden changes, not small fluctuations.
7. Clean Up Your List and Sending Practices
Tools can only take you so far. If you’re still hitting deliverability walls, it’s time to look at your list and your habits.
What matters: - Are you sending to people who actually want your emails? - Are you removing hard bounces and unsubscribes quickly? - Are you sending at a reasonable frequency (not blasting every day)?
What to ignore:
Don’t buy lists. Ever. No tool will fix the reputation damage from that.
8. Troubleshooting Checklist
Here’s a quick checklist you can run every time before sending a campaign:
- [ ] Authentication: SPF, DKIM, DMARC all pass
- [ ] Spam Test: No major filter failures in Litmus
- [ ] Rendering: Looks good in top clients (Gmail, Outlook, Apple Mail, mobile)
- [ ] Links & Images: No broken or blacklisted links/images
- [ ] List: Clean, no purchased contacts, bounces removed
- [ ] Unsubscribe: Easy to find and works
If any of these fail, fix them before you send. It’s worth the extra five minutes.
Keep It Simple and Iterate
Email deliverability isn’t a one-and-done project. The best senders keep things simple: send to people who want your emails, keep your lists clean, use the tools for what they’re good at, and don’t fall for shiny objects or miracle fixes.
Litmus gives you the visibility to spot problems before they become disasters—but it’s only as good as the sender behind it. Keep testing, keep improving, and don’t sweat the clients nobody uses. Inbox placement is a moving target. The good news? Most issues are fixable if you’re willing to look under the hood and make small changes, one send at a time.