How to Stop Emails from Going to Spam (Complete Guide)

Your emails are going to spam, and chances are, you know exactly which ones.

The welcome email that 30% of users never see. The password reset that arrives 10 minutes late, buried under promotions. The product update that half your customers miss entirely.

Here's what's frustrating: it's probably not your email content that's the problem. It's technical mistakes that are completely fixable but easy to miss if you don't know what spam filters are looking for.

I run AutoSend, an email service provider, and I see these mistakes constantly. A founder will email me confused about why their deliverability tanked overnight. I'll look at their setup and immediately spot it: they're using noreply@, or they just sent 10,000 emails from a week-old domain, or they deleted their suppression list and re-uploaded contacts.

These aren't edge cases. They're the most common reasons emails land in spam.

This guide covers 18 mistakes that destroy email deliverability, organized by severity. Some are critical and will get you blacklisted fast (like bypassing unsubscribes). Others are medium-impact but still hurt your sender reputation over time (like too many links or poor text-to-image ratios).

For each mistake, I'll explain what's wrong, why spam filters flag it, and exactly how to fix it. By the end, you'll have a checklist to audit your own email setup and stop losing emails to the spam folder.

Let's start with the critical ones.

Missing Email Authentication (SPF, DKIM, DMARC)

Inbox providers automatically flag unauthenticated emails as potential impersonation attempts. Without these three protocols configured, your emails have no way to prove they're legitimately from you. Set them up in your DNS records and verify they're working with authentication checkers.

Using noreply@ or no-reply@ Addresses

These addresses signal to spam filters that you don't want engagement, which is exactly what spam does. ESPs prioritize emails that encourage two-way communication. Use real addresses like hello@, support@, or team@ instead.

You can use these emails for transactional email once your sending domain reputation is built. This typically takes 6 to 8 months. But I will recommend after 12 months.

Deleting Contacts and Re-uploading to Bypass Unsubscribes

This violates CAN-SPAM and GDPR laws, and users will hit the spam button when they get emails they already unsubscribed from. Your sender reputation tanks instantly. Suppression lists exist for a reason - respect them permanently. If you want to re-engage people, use proper win-back campaigns for legitimately disengaged users.

Missing Unsubscribe Link and Postal Address in Footer

CAN-SPAM requires both a working unsubscribe mechanism and a physical postal address in every commercial email. Without these, you're breaking the law and giving users no choice but to report you as spam. Every email needs a clear, one-click unsubscribe option and your business address in the footer.

High-Impact Mistakes:

The next group of mistakes won't get you blacklisted overnight, but they'll steadily destroy your sender reputation. These are especially common with new domains or aggressive growth strategies. If you're seeing gradual deliverability decline or struggling to scale your email volume, you're probably making one of these:

Sending Bulk Emails with Brand New Domain

A brand new domain has zero sender reputation. When you immediately blast thousands of emails from it, you look exactly like a spam operation. Warm up your domain over 2-4 weeks, starting with 50-100 emails per day to engaged contacts, then gradually increase volume.

Cold Emailing with New Domain

Combine an unknown sender with unsolicited emails and you've got a double red flag. Even legitimate cold outreach needs a warmed domain first. Start with engaged contacts for a few weeks, then begin cold outreach slowly with smaller volumes. Do read the domain warmup guide.

Using URL Shorteners (bit.ly, tinyurl, etc.)

Spammers use these to hide malicious destinations, so filters treat them as red flags. Use full URLs in your emails, or if you must track clicks, use custom domain short links with proper authentication.

You don't have to worry about this if you're tracking clicks in AutoSend because we replace your links with our branded tracking domain.

Purchased or Scraped Email Lists

These lists contain spam traps, inactive addresses, and people who never gave permission. Your reputation gets destroyed immediately. Only email people who explicitly opted in to hear from you.

Using Different Domains for From and Reply-To Addresses

When your From address is @company.com but Reply-To is @differentorg.com, it looks like you're trying to hide something. This is a classic phishing technique. Keep both addresses on the same authenticated domain.

Medium-Impact Mistakes

These mistakes won't tank your reputation immediately, but they add up. Each one increases your spam score incrementally, and when you combine several of them, you start seeing problems. They're also the easiest to fix, most requiring simple content or formatting changes:

Overly Designed Emails (Poor Text-to-Image Ratio)

Emails that are mostly images with little text look like advertisements and give spam filters nothing to analyze. Keep a 60/40 or 70/30 text-to-image ratio and always include a plain text version.

Too Many Links in One Email

Each link increases your spam score, and 10+ links screams spam. Keep it to 3-5 links maximum and make each one count.

Ignoring Bounces and Complaints

Continuing to send to addresses that hard bounce or users who complained destroys your sender reputation. Automatically suppress hard bounces and monitor complaint rates closely.

Generic or Spammy Subject Lines

Subject lines with "URGENT!!!", "FREE $$$", "Re: [nothing]" trigger spam filters instantly and look untrustworthy. Write clear, honest subject lines that accurately describe the email content.

Creating False Urgency in Email Copy

Phrases like "ACT NOW!", "Limited time only!", "Expires in 24 hours!" are spam filter triggers and erode trust. Even if you have a legitimate deadline, present it factually without manufactured pressure. Real urgency doesn't need ALL CAPS and multiple exclamation marks.

Not Personalizing Emails (Using "Dear Friend" or "Hey There")

Generic greetings like "Hello dear" or "Hey friend" tell the recipient you don't actually know them, which is exactly what spam does. Use their actual name if you have it. If you're sending to people whose names you don't have, you probably shouldn't be emailing them at all.

Excessive Capitalization and Exclamation Marks!!!

WRITING IN ALL CAPS or using multiple exclamation marks!!! makes you look unprofessional and triggers spam filters. Write like a normal person having a conversation, not someone shouting from an infomercial.

Closing note

You don't need to fix all 18 mistakes at once. Start with the critical ones, especially email authentication and anything involving legal compliance. Those will give you the biggest deliverability improvement immediately.

Then work through the high-impact mistakes, particularly if you're using a new domain or seeing inconsistent inbox placement. The medium-impact fixes can come last, but don't ignore them since they compound over time.

The good news: most of these are one-time fixes. Set up authentication correctly once, use real email addresses, respect suppression lists, and you've eliminated half the list. The rest are about content and sending patterns, which get easier once you know what to avoid.

Fix these mistakes, and your emails will start landing in inboxes instead of spam folders.