Emails Going to Spam? Here’s How to Fix It

You build a great product, craft a thoughtful message, hit send... and then your user says, “I didn’t get the email.” So you check your logs, everything looks fine, but the message is sitting quietly in their spam folder. Oops, embarrassing!

This is one of the most frustrating parts of running an app or sending transactional emails. The good news? It’s almost always fixable once you understand what’s going wrong.

Let’s unpack why emails go to spam and how you can keep yours landing safely in the inbox.

You haven’t set up proper email authentication

This is the number one reason your emails end up in spam.

If your domain isn’t authenticated, email providers like Gmail or Outlook can’t confirm the message is really coming from you. So, to protect users, they flag it as suspicious.

Set up three essential DNS records:

• SPF – lists the servers allowed to send emails for your domain.

• DKIM – adds a digital signature to prove the email wasn’t modified.

• DMARC – tells providers what to do when an email fails SPF or DKIM checks.

Once you configure these correctly, you’ll see a noticeable improvement in inbox placement. Tools like Mail-Tester, MXToolbox, or DMARCian can help verify your setup.

Your sending domain or IP has a poor reputation

Every domain and IP has a reputation score that mailbox providers use to decide where your emails go. If too many of your messages get flagged, bounced, or ignored, your reputation drops, and your next emails are more likely to be filtered as spam.

Common causes include:

• Sending large batches too quickly

• Using shared IPs with other senders who spam

• Getting high bounce or complaint rates

To fix this:

• Warm up new domains gradually instead of blasting thousands of emails on day one.

• Use dedicated IPs if you send high volume.

• Keep your bounce rate below 2% and complaint rate below 0.1%.

Think of your sender reputation like a credit score. Consistency, trust, and history matter more than speed.

Your email content looks spammy

Spam filters scan the content of your emails before they reach the inbox. Even if your authentication is perfect, your copy and formatting can still trigger a filter.

Here’s what to watch out for:

• Overuse of “FREE,” “LIMITED TIME,” or “CLICK NOW.”

• Too many images with little text.

• Broken HTML or messy inline styles.

• No plain text version of the email.

• Missing unsubscribe link in marketing emails.

Keep your design simple and your tone natural. Write like you’re talking to a person, not pitching a crowd. Always include a clear sender name, recognizable address, and valid contact info.

Pro tip: Before sending a campaign, run it through a spam-check tool to see how filters interpret your content.

You’re sending from a new or cold domain

If your domain is brand new or has never sent emails before, providers don’t trust it yet. That’s normal.

Start slow. Send small batches to verified or internal addresses, build up a positive history, and monitor engagement. This process is known as domain warming.

You can also use a subdomain for your email traffic, like mail.yourdomain.com or notifications.yourdomain.com. This keeps your main domain safe if something goes wrong.

Remember, reputation builds over time. The key is steady, consistent sending behavior.

You’re not monitoring your delivery performance

Email deliverability isn’t a one-time setup. It’s something you have to monitor continuously.

Keep an eye on:

• Bounce logs: Which addresses are failing and why.

• Open and click rates: Low engagement signals filters that your emails aren’t wanted.

• Spam complaints: Even a small spike can affect your reputation.

Most modern email platforms provide dashboards or webhook logs for this data. Reviewing them weekly helps you spot patterns before they become serious problems.

If you’re sending through APIs or services like AutoSend, you can use Email Activity feature to track your delivery rate and fix authentication or content issues fast.

You’re mixing transactional and promotional content

This is an easy mistake to make. Transactional emails are system messages triggered by user actions (signup confirmations, password resets, invoices). Promotional emails are sent to promote something (updates, offers, new features).

Mixing them confuses both users and spam filters. For example:

“Your password has been reset successfully. Here’s a 30% discount on your next order.”

That’s not a transactional email anymore. Keep them separate. Use different templates, sender names, or subdomains for each type.

This clarity helps you stay compliant with laws like CAN-SPAM and improves overall inbox placement.

You’re sending without user consent

Even if you have the best infrastructure, sending emails to people who didn’t opt in is a fast track to the spam folder.

Always collect consent before sending marketing messages. Use double opt-in where users confirm their subscription. Make it easy to unsubscribe or change preferences at any time.

Trust is a long-term deliverability strategy. The fewer complaints you get, the stronger your domain reputation becomes.

Test before you send

Before sending anything to your full list, send test emails to a few different accounts (Gmail, Outlook, Yahoo) and check where they land.

If they consistently show up in spam, inspect the headers and test against spam score tools. Small tweaks in authentication, copy, or formatting can often make the difference.

Landing in the spam folder doesn’t mean your emails are doomed. It’s usually a sign that one or two technical or behavioral factors need attention.

Start with authentication, check your domain reputation, simplify your content, and watch your logs. Over time, your inbox placement will improve and stay consistent.

Good deliverability is not luck. It’s the result of clean setup, good habits, and trust built over time.