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

Estimated reading time: 10 minutes

SendGrid is a powerful email delivery platform used by businesses for transactional emails, marketing campaigns, product notifications, newsletters, and automated customer communication. But using SendGrid alone does not guarantee that every email will land in the inbox.

Many senders discover that their emails are marked as spam, filtered into promotions, delayed, blocked, or quietly ignored by recipients. This usually happens because inbox placement depends on more than the email service provider. Mailbox providers look at your domain reputation, authentication setup, sending behavior, list quality, engagement, complaint rates, and email content before deciding where your message should go.

In this article, we’ll talk about why SendGrid emails go to spam and how to improve inbox placement step by step.

Key Takeaways

• SendGrid does not automatically guarantee inbox placement.
• Emails may go to spam because of poor sender reputation, weak authentication, bad list quality, or low engagement.
• SPF, DKIM, and DMARC are essential for proving that your emails are legitimate.
• New domains, new IPs, and sudden volume increases should be warmed up gradually.
• Transactional and marketing emails should be separated to protect critical messages.
• Clean lists, relevant content, and consistent sending behavior improve deliverability.
• Tools like GlockApps can help test inbox placement and identify spam filtering issues before they damage campaign performance.

Why SendGrid Emails Go to Spam

SendGrid is only one part of the email delivery process. It helps you send emails, but mailbox providers such as Gmail, Outlook, Yahoo, and others decide whether those emails reach the inbox, spam folder, or get blocked.

Here are the most common reasons SendGrid emails go to spam.

1. Your Domain Is Not Properly Authenticated.

Email authentication tells inbox providers that your messages are legitimate and that SendGrid is allowed to send on behalf of your domain. Without proper authentication, your emails may look suspicious.

The three main authentication protocols are:

• SPF: Confirms which servers are allowed to send email for your domain.
• DKIM: Adds a digital signature to your emails to prove they were not altered.
• DMARC: Tells mailbox providers what to do when SPF or DKIM checks fail.

SendGrid offers domain authentication and automated security features that help configure SPF and DKIM records. SendGrid also explains that DMARC helps domain owners define what should happen when SPF or DKIM fails, while also improving visibility into authentication problems.

How to Fix It

To improve authentication:

• Set up SendGrid domain authentication.
• Make sure SPF includes SendGrid correctly.
• Enable DKIM signing for your sending domain.
• Add a DMARC record.
• Start with a monitoring policy such as p=none.
• Move toward stricter DMARC policies only after reviewing reports.
• Make sure your visible From domain aligns with your authenticated domain.

Authentication alone will not guarantee inbox placement, but without it, good deliverability becomes much harder.

2. Your Sender Reputation Is Weak or Damaged.

Sender reputation is one of the biggest factors behind spam placement. Inbox providers build a reputation profile for your sending domain and IP address based on your past behavior.

Your reputation can suffer when you have:

• High bounce rates
• Spam complaints
• Low click rates
• Sudden spikes in volume
• Emails sent to inactive users
• Poor list acquisition practices
• Repeated sending to people who do not engage

If mailbox providers see that recipients ignore, delete, or mark your SendGrid emails as spam, future messages are more likely to be filtered.

How to Fix It

To rebuild sender reputation:

• Send only to people who clearly opted in.
• Remove invalid, inactive, and risky contacts.
• Avoid purchased or scraped lists.
• Reduce sending volume if spam placement suddenly increases.
• Focus on your most engaged contacts first.
• Monitor bounce rates and spam complaints.
• Keep your sending frequency consistent.

Reputation recovery takes time. You cannot fix it with one DNS change or one campaign adjustment. You need consistent positive sending behavior.

3. You Are Sending Too Much Too Quickly.

A common mistake is sending a large volume of email from a new domain, new SendGrid account, or new dedicated IP without warming it up.

Mailbox providers are cautious with new senders. If a domain or IP suddenly sends thousands of emails without a history of trusted behavior, inbox providers may treat that activity as suspicious.

How to Fix It

Warm up your sending gradually:

• Start with a small volume.
• Send first to your most engaged contacts.
• Increase daily or weekly volume slowly.
• Watch bounce rates, complaints, and engagement.
• Avoid sudden campaign spikes.
• Pause scaling if spam placement increases.

For dedicated IP users, IP warm-up is especially important. For shared IP users, domain reputation still matters, so a new domain should also build trust gradually.

4. Your Email List Quality Is Poor.

Even well-written emails can go to spam if they are sent to the wrong list.

Poor list quality includes:

• Invalid addresses
• Old contacts
• Purchased leads
• Scraped emails
• Role-based addresses
• Unengaged subscribers
• People who never gave clear permission

Bad lists create bad signals. They increase bounces, spam complaints, unsubscribes, and low engagement.

How to Fix It

Improve list quality by:

• Using confirmed opt-in when possible.
• Removing hard bounces immediately.
• Suppressing people who repeatedly do not engage.
• Validating emails before large campaigns.
• Avoiding purchased or scraped lists.
• Segmenting contacts by behavior and interest.
• Running re-engagement campaigns before removing inactive subscribers.

A smaller engaged list is better than a large list that damages your reputation.

5. Your Email Content Looks Suspicious.

Spam filters also evaluate email content. Even if your technical setup is correct, your message may still trigger filtering if it looks risky, misleading, or low-quality.

Common content problems include:

• Misleading subject lines
• Too many links
• Link shorteners
• Excessive images
• Weak text-to-image balance
• All-caps language
• Too many promotional phrases
• Poor formatting
• Broken HTML
• Missing unsubscribe option
• Mismatch between the From name, subject, and email body

How to Fix It

Improve your email content by:

• Writing clear and honest subject lines.
• Keeping the message relevant to the recipient.
• Avoiding exaggerated claims.
• Using a clean HTML structure.
• Balancing text and visuals.
• Limiting unnecessary links.
• Making the unsubscribe option easy to find.
• Testing emails before sending.
• Personalizing content based on the recipient’s needs or behavior.

The goal is not to “trick” spam filters. The goal is to send emails that people actually want to receive.

6. You Are Mixing Transactional and Marketing Emails.

Transactional emails and marketing emails serve different purposes.

Transactional emails include:

• Password resets
• Account confirmations
• Receipts
• Shipping updates
• Security alerts
• Product notifications

Marketing emails include:

• Newsletters
• Promotions
• Announcements
• Sales campaigns
• Re-engagement emails

If you send both types from the same domain or IP, poor performance from marketing campaigns can affect important transactional messages. SendGrid recommends separating email streams because it helps protect legitimate mail and improves long-term deliverability.

How to Fix It

Separate your mail streams:

• Use different subdomains for transactional and marketing emails.
• Keep transactional emails clean and functional.
• Avoid promotional content in transactional messages.
• Monitor each stream separately.
• Protect critical messages from marketing-related reputation issues.

For example, you might use one subdomain for account notifications and another for newsletters.

7. Your Engagement Signals Are Too Low.

Mailbox providers care about how recipients interact with your emails. Positive engagement can support inbox placement, while negative or weak engagement can hurt it.

Positive signals include:

• Clicks
• Replies
• Moving emails from spam to inbox
• Marking messages as important
• Reading messages regularly

Negative signals include:

• Spam complaints
• Deleting without opening
• Ignoring repeated emails
• Unsubscribing
• Leaving emails unread

SendGrid notes that recipient interaction affects deliverability, and that wanted messages are more likely to reach the inbox.

How to Fix It

Improve engagement by:

• Segmenting your audience.
• Sending more relevant content.
• Personalizing based on behavior.
• Avoiding over-sending.
• Removing inactive contacts.
• Testing subject lines.
• Sending at times when your audience is more likely to engage.
• Making every email useful, clear, and expected.

Inbox placement improves when recipients consistently show that they want your emails.

8. You Are Not Monitoring Inbox Placement.

Many SendGrid users only check delivery rates. But delivery rate does not tell you whether emails landed in the inbox or spam.

An email can be marked as “delivered” and still end up in the spam folder. That is why inbox placement testing is important.

You should monitor:

• Inbox vs. spam placement
• Authentication results
• Sender reputation
• Bounce patterns
• Spam complaints
• Blocklist status
• Engagement trends
• Performance by mailbox provider

GlockApps can help by showing where your emails land across different mailbox providers and helping you identify deliverability issues before they affect a larger campaign.

9. Your Sending Frequency Is Inconsistent.

Inconsistent sending patterns can also hurt deliverability.

For example, if you send nothing for weeks and then suddenly send a large campaign, mailbox providers may treat the spike with caution. The same can happen if you send too frequently and recipients stop engaging.

How to Fix It

Build a predictable sending rhythm:

• Send consistently.
• Avoid sudden volume spikes.
• Match frequency to user expectations.
• Let subscribers choose preferences when possible.
• Reduce frequency for less engaged contacts.
• Increase volume gradually during campaigns.

Consistency helps mailbox providers understand your normal sending behavior.

10. You Ignore Bounce and Complaint Data.

SendGrid gives senders access to performance data, but many teams do not review it often enough. Bounce and complaint patterns can reveal serious deliverability problems.

Watch for:

• Rising hard bounces
• Repeated soft bounces
• Blocks from specific mailbox providers
• Increased spam complaints
• Drops in opens or clicks
• Sudden domain-level issues

How to Fix It

Use your data actively:

• Remove hard bounces.
• Investigate blocks quickly.
• Suppress complainers.
• Compare performance by domain.
• Look for campaign-specific issues.
• Stop sending to segments that damage reputation.

Deliverability is not something you check once. It needs ongoing monitoring.

Step-by-Step Checklist to Stop SendGrid Emails from Going to Spam

Use this checklist to improve your SendGrid inbox placement:

1. Authenticate your domain
   • Set up SPF, DKIM, and DMARC.
   • Make sure your domain alignment is correct.
2. Check your sender reputation
   • Review bounce rates, complaints, and engagement.
   • Reduce volume if reputation is declining.
3. Warm up gradually
   • Start with engaged recipients.
   • Increase volume slowly.
4. Clean your list
   • Remove invalid, inactive, and risky addresses.
   • Avoid purchased or scraped contacts.
5. Improve your content
   • Use honest subject lines.
   • Avoid spammy formatting.
   • Keep emails clear, relevant, and useful.
6. Separate email streams
   • Use different subdomains for transactional and marketing emails.
7. Monitor inbox placement
   • Test where emails land before sending large campaigns.
   • Use GlockApps to identify spam placement, authentication issues, and provider-specific deliverability problems.

8. Track performance over time

• Watch engagement, complaints, bounces, and blocks.
• Adjust your strategy based on real data.

Conclusion

SendGrid emails usually go to spam because of a combination of technical, reputational, and engagement issues. The platform can help you send emails at scale, but inbox placement depends on how trustworthy your domain looks to mailbox providers and how recipients respond to your messages.

To improve SendGrid deliverability, start with the basics: authenticate your domain, clean your list, warm up gradually, separate transactional and marketing emails, and monitor inbox placement regularly. Then focus on sending emails that people actually expect, open, and engage with.