If your B2B emails keep landing in spam, you’re not alone. Most marketers have been there—crafting the perfect message, hitting send, and then… crickets. If you want your emails to actually show up in inboxes (not the dreaded junk folder), you’ve got to get serious about spam testing. This guide breaks down how to use Litmus to do just that—without the fluff or false promises.
Who’s this for? Anyone sending serious B2B campaigns who’s tired of guessing why emails disappear. Whether you’re a one-person marketing shop or managing a big list, this is for you.
Step 1: Understand What Litmus Spam Testing Actually Does (and Doesn’t)
Litmus promises to help you catch issues before you send. It checks your email against real spam filters (think Outlook, Gmail, Barracuda, etc.) and gives you a sense of how your message might fare.
But here’s what Litmus won’t do: - Guarantee inbox placement (no tool can, honest) - Fix deliverability issues you create by sending to bad lists - Override poor sending reputations
What it’s good for: - Catching obvious red flags (bad links, dodgy images, weird code) - Seeing how actual spam filters react to your message - Giving you a fighting chance at getting to the inbox
If you expect magic, you’ll be disappointed. If you want a reality check before you send, you’re in the right place.
Step 2: Set Up Your Litmus Account and Integrate With Your ESP
You’ll need a Litmus account (not free, and not cheap—but worth it if email matters to your business). Once you’re in:
- Connect Litmus to your email service provider (ESP), if possible. Many big ESPs (like Mailchimp, Salesforce, HubSpot) have direct integrations.
- If there’s no direct integration, you can still send test emails to Litmus manually.
Pro tip: You get more value from Litmus if you set up integrations. It’s less hassle in the long run.
Step 3: Build a Realistic Test Email
It’s tempting to test a bare-bones message, but that’s not what your audience gets. Spam filters judge the whole email, including: - Subject line and sender name - Body content (text, images, links) - Footer and unsubscribe info - Tracking codes and custom headers
So test the real thing. Pull your actual campaign from your ESP, with all personalization, links, tracking, and formatting included.
Step 4: Run the Spam Filter Tests
Inside Litmus, use the “Spam Testing” or “Pre-Send” tools. Here’s what happens:
- Litmus sends your email to dozens of test accounts (Gmail, Office 365, Yahoo, etc.).
- It checks your message against common spam filters: Barracuda, Symantec, Outlook, Proofpoint, and more.
- You get a dashboard showing which filters flagged your message, and why.
What’s actually useful: - Seeing a “spam verdict” for each filter (pass/fail, with reasons) - Details on what triggered the filter (bad links, failed authentication, spammy words)
What’s not so useful: - Overanalyzing tiny warnings (some flags, like “low image-to-text ratio,” are almost unavoidable in B2B) - Worrying about consumer-focused spam filters (focus on the filters your audience actually uses—mainly Outlook, Gmail, and whatever big security gateways your clients run)
Step 5: Read the Results With a Skeptical Eye
Spam filter tests are helpful, but not gospel. Here’s how to make sense of what you see:
- Authentication fails (SPF, DKIM, DMARC): These are red alerts. Fix them ASAP—your IT or ESP support can help. Without these, you’re dead in the water.
- Blacklists: If your sending domain, IP, or a link in your email is on a blacklist, that’s a bad sign. Sometimes it’s an error, sometimes you really are listed. Litmus shows you the details.
- Spammy content: Words like “free,” “guarantee,” or “act now” might trigger some filters, but don’t obsess. In B2B, these aren’t as much of a problem unless you’re going over the top.
- Broken links or images: These look suspicious to filters. Fix them.
- Missing unsubscribe links: Not just a legal issue—spam filters look for this too.
Ignore: - Minor formatting warnings (most B2B recipients are on Outlook or Gmail, which handle code pretty well) - “Image-to-text” ratio warnings, unless you really are sending an all-image email (which you shouldn’t)
Step 6: Fix Only What Matters
Don’t try to get a perfect score on every spam filter—some are impossible to please, and your real audience doesn’t use all of them. Focus on:
- Passing authentication (SPF, DKIM, DMARC)
- Avoiding obvious blacklists
- Fixing broken links, placeholder text, or missing unsubscribe info
- Making sure your From name, subject, and reply-to look legit (no “noreply@” if you can avoid it)
If you’re failing Barracuda, Outlook, or Gmail spam filters, that’s worth digging into. If you’re failing obscure filters, don’t lose sleep.
Quick fixes: - Swap out flagged links for clean ones (especially if using link shorteners) - Remove spammy language in subject lines (but keep it natural—no need to sound like a robot) - Make sure your HTML is clean and not full of ancient code
Step 7: Test With Real Seed Lists (If You’re Paranoid)
Litmus spam testing is good, but nothing beats sending a test to real inboxes. Create a “seed list” of test accounts at the major providers your clients use (Gmail, Outlook, Yahoo, corporate domains if you can). Send your campaign to these accounts and see where it lands.
Pro tip: Sometimes a message passes all the Litmus tests but still gets clipped, flagged, or lands in “Other” tabs. A seed list lets you see the real-world outcome.
Step 8: Keep an Eye on Deliverability Over Time
Spam testing is not a “set it and forget it” thing. Filters change, your reputation shifts, and what passes today might fail next month. Keep an eye on:
- Open rates (a sudden drop can mean deliverability issues)
- Bounces and spam complaints
- Feedback from sales or clients (“Hey, your email went to my junk folder”)
Make spam testing a regular part of your process, not a one-off fix.
What to Ignore (and What Not to Buy)
Some marketers get caught up in “deliverability hacks” or buy into every new tool that promises perfect inboxing. Here’s what to skip:
- “Guaranteed inbox placement” services: No one can guarantee this, not even Litmus.
- Overly complex deliverability tools: If you’re already using Litmus and your ESP’s built-in tools, you’re covered for 95% of cases.
- Obsessing over minor warnings: Focus on the big stuff that actually impacts B2B delivery.
Save your money and energy for things that actually move the needle.
Summary: Keep It Simple and Iterate
Don’t overthink it. Use Litmus to catch the obvious issues, double-check with real inboxes when it matters, and focus on sending emails people actually want. Make small tweaks, watch your results, and remember—no tool will fix a bad list or boring content.
Spam testing with Litmus isn’t glamorous, but it beats guessing. Keep your process lean, fix what matters, and hit send with confidence.