Why are my emails going to spam? | AgentMail

If your agent’s emails are landing in spam instead of the inbox, work through these common causes in order. The most frequent issues are at the top.

1. Missing or incorrect DNS records

This is the most common cause. SPF, DKIM, and DMARC must all be configured correctly for receiving servers to trust your emails.

How to check: Go to the AgentMail Console, navigate to Domains, and verify that all records show as verified.

If any records are missing or misconfigured, see the SPF, DKIM, and DMARC setup guide.

2. New domain without warmup

New domains have zero sender reputation. If you start sending hundreds of emails immediately, providers will flag your domain as suspicious.

Fix: Warm up gradually:

Timeframe	Volume
Week 1	10 to 20 emails per day
Week 2	50 to 100 emails per day
Week 3	Scale up based on engagement

Maintain low bounce rates and low spam complaint rates throughout. See the domain warming schedule for a detailed plan.

3. Sending HTML without a text version

Always include both html and text versions of your email. Spam filters flag emails that contain only HTML with no plain text fallback.

TypeScript

1 await client.inboxes.messages.send(inbox.inboxId, {
2   to: "user@example.com",
3   subject: "Hello",
4   text: "Plain text version of your email",
5   html: "<p>HTML version of your email</p>",
6 });

4. Spammy content

Email providers use content analysis to flag spam. Avoid these patterns in your subject lines and body:

ALL CAPS subjects
Excessive exclamation marks
Trigger words like “FREE”, “BUY NOW”, “ACT NOW”, “URGENT”
Too many links in a single email
Large images with very little text

5. High bounce rate

Sending to invalid email addresses damages your sender reputation quickly. If too many emails bounce, providers start sending your future emails to spam.

Fix: Validate email addresses before sending. Remove bounced addresses from your lists immediately. You can track bounces using the message.bounced webhook event.

6. Using @agentmail.to for production

The shared @agentmail.to domain is great for testing, but it has shared reputation across all users. For production sending, consider using a custom domain with proper DNS authentication.

Still landing in spam?

If you have checked all of the above and emails are still going to spam, reach out in our Discord support channel.

For a comprehensive guide to maximizing deliverability, see the Email Deliverability best practices.