If you’ve ever sent an email campaign only to wonder “why is nobody opening this?”, chances are your emails might be landing in spam. Inbox providers (Gmail, Outlook, Yahoo, etc.) are like strict bouncers at a club, they check your reputation before letting your message in.
The good news: you can totally influence this. Here’s how to build trust, stay out of spam, and get your emails where they belong - in front of your audience.
What affects your domain reputation
Your domain reputation is basically your trust score with inbox providers. Here’s what they’re watching:
Engagement: Do people open, read, click, or just delete your emails?
Complaints: Even a tiny % of “mark as spam” hurts.
List hygiene: Sending to invalid addresses or spam traps is not good!
Bounces: Dead inboxes drag your reputation down.
Spam traps: Fake addresses set up to catch spammers.
Content quality: Clear, relevant, not spammy.
Sending behavior: Are you consistent or blasting huge spikes randomly?
Important: Your reputation sticks. Switching platforms or IPs won’t save you if your domain’s history is messy. Rebuilding trust takes time.
Improving your email deliverability
Step 1: Get your domain set up right
This is the foundation. If your domain isn’t verified properly, you’ll be treated like a stranger at the door.
SPF (Sender Policy Framework) → Think of it as the guest list. It tells inboxes which servers are allowed to send email on your behalf.
DKIM (DomainKeys Identified Mail) → A digital signature that proves your email wasn’t altered in transit.
DMARC (Domain-based Message Authentication) → Instructions for inboxes: “If SPF/DKIM checks fail, here’s what to do.”
How to check:
Use free tools like MXToolbox, Google Admin Toolbox CheckMX, or dmarcian
Enter your domain (e.g.
yourcompany.com) and see if SPF, DKIM, and DMARC are set up correctly.This is how a correctly configured domain looks in MXToolbox:
If you see any red icons instead of green checkmarks, then that is an indication of incorrect configuration.
Step 2: Keep your emails clean and professional
Even if your domain and authentication are perfect, messy email content can still send you straight to the spam folder. Spam filters scan the structure and formatting of your messages as carefully as the address they are coming from.
Key points:
Balance text + images. Don’t send one big graphic or image-heavy emails. Aim for a natural mix so your message feels readable, not like a flyer.
Watch your wording. Too many !!!, ALL CAPS, or pushy sales phrases (“BUY NOW,” “FREE!!!”) will get flagged. Subject lines should always match the content, no tricks or clickbait.
Use safe links. Stick with full, branded URLs. Link shorteners or suspicious domains look risky to filters.
Limit attachments. PDFs, Word docs, and ZIP files can trigger security warnings. Instead, share a link to your file on a trusted site.
Format neatly. Clean, professional design builds trust. A well-structured, typo-free email is better for both readers and inbox placement.
Clean, professional formatting doesn’t just improve deliverability: it also builds trust with your readers and makes them more likely to engage.
Step 3: Send from a recognizable address
Your “From” address is one of the strongest signals inboxes (and humans) use to judge trust. This is why you always want to use your own company's domain and keep it consistent.
Sending from a custom domain (e.g. you@yourcompany.com) looks professional, builds trust with your recipients, and allows you to configure authentication properly. Over time, your domain earns credibility as people open and engage with your emails, making inbox placement far more reliable.
Step 4: Warm up new domains
If you’re sending from a brand-new domain, inboxes are extra cautious. Dropping hundreds of emails on day one is a fast way to get flagged.
Start small. Send 20–30 emails per day in the first week.
Increase gradually. Double or add 20–30 more each week.
Focus on engaged recipients. Send to people most likely to open and click (friends, colleagues, loyal customers). High engagement builds positive reputation faster.
Warming up shows inbox providers you’re a real sender who people actually want to hear from.
Step 5: Control your sending
Consistency is key. Spam filters don’t like surprises.
Be predictable. Don’t go silent for months and then blast thousands of emails.
Keep volumes steady. Sudden spikes look like suspicious activity.
Segment your audience. Send smaller, relevant batches instead of one giant campaign to everyone.
Step 6: Track and adjust
If your open rates drop suddenly or bounce rates spike, something’s off.
Monitor key metrics: open rates, click rates, bounce rates, spam complaints.
Test subject lines and content styles.
If deliverability issues persist, check your domain reputation with tools like Google Postmaster Tools.
Common mistakes to avoid
Sending from a free Gmail/Yahoo address instead of your domain
Ignoring unsubscribe requests (nothing screams spam louder)
Sending too fast, too soon (especially from a new domain)
Overusing salesy, spammy language
Attaching large files instead of linking
The bottom line is that by setting up your domain correctly, sending professional and consistent emails, keeping your list healthy, and tracking performance, you’ll earn inbox trust and your emails will reliably reach the people who want them.
If you have any questions or are struggling, ping us either on chat or hello@modash.io. We're happy to help!