How to Stop SendGrid Emails from Going to Spam and Improve Inbox Placement

According to a 2025 deliverability report, about 17.47% of SendGrid emails are routed to spam folders after successful delivery, while around 3.71% fail to reach recipients. The high spam rate highlights the core challenge many SendGrid users face. Even with a strong delivery rate, nearly one in six emails still land in spam.

If your SendGrid emails are going to spam, you’re not alone. Many marketers and businesses experience this, especially when sending bulk or cold outreach emails.

SendGrid was built primarily for transactional messages and newsletter emails, which typically achieve stronger inbox trust because of consistent recipient engagement and clear user intent. However, when SendGrid is used for B2B cold outreach or mass promotional campaigns, deliverability depends heavily on sender reputation, authentication, and engagement.

This guide will help you understand:

• Why SendGrid emails go to spam
• How to diagnose deliverability problems
• What precise steps you can take to improve email deliverability and inbox placement
• How to use tools such as MailReach’s email warmup and email spam test to monitor and regain inbox visibility

Why SendGrid Emails Land in Spam?

When your emails sent via SendGrid land in spam, the issue is not entirely with SendGrid. It’s about the signals inbox providers see from your sending behavior, domain setup, and audience engagement. Platforms like Gmail and Outlook rely on complex algorithms that score every message before deciding its placement: inbox, promotions, or spam.

At a high level, deliverability depends on three core pillars:

• Sender reputation: Your sender reputation is built on engagement. High opens, replies, and low complaint rates signal trust. But high bounces, spam complaints, or sudden spikes in volume tell inbox providers your domain might be risky, causing messages to land in spam.
• Sending setup and authentication: Accurate SPF, DKIM, and DMARC records prove that your emails are legitimate. If these protocols are missing or misconfigured, providers can’t verify your identity and unverified domains lose trust fast.

Content quality: Your content also influences placement. Well-formatted, relevant messages with a clean design, balanced text-to-image ratio, and compliant unsubscribe links perform better. On the other hand, excessive promotional language, heavy images, or spam-trigger words can instantly flag your emails.

For transactional emails such as receipts or password resets, filters expect predictable volume and clear user intent. These typically land in the inbox because recipients anticipate them. Bulk or marketing sends, especially cold or newsletter emails, face major scrutiny, engagement and consent vary.

If you notice emails from SendGrid going to spam, the issue lies in how mailbox providers interpret your domain activity, not in the platform itself. Understanding these signals is the foundation for diagnosing and improving SendGrid inbox placement.

Quick SendGrid Deliverability Fixes for Immediate Results

Before diving into complex deliverability fixes, run this short diagnostic to catch the most common SendGrid issues early.

Stop SendGrid Emails from Going to Spam: 9-Step Fix

When SendGrid emails go to spam, a fix that lasts requires more than surface-level tweaks. 

First, separate what’s technical vs behavioral. Technical issues come from rented SMTP servers, setup errors, missing protocols or link branding, while engagement issues stem from poor response rates, inactive lists, or cold campaign fatigue.

Categorizing events this way transforms vague spam problems into insights. Here’s what you should do. 

• Prioritize fixing network, authentication and building domain trust. 
• Focus on improving content quality and recipient engagement.

This approach provides a clear, objective baseline for all future SendGrid deliverability improvements.

Below is a clear, repeatable process teams can follow to diagnose and permanently repair inbox delivery issues.

1. Fixing Domain Authentication Properly

Before any content or send volume improvements make a difference, mailbox providers first look for proof that your emails are legitimate. That proof comes from three domain authentication protocols, SPF, DKIM, and DMARC, and the often-overlooked link branding (tracking domain alignment) setup within SendGrid.

Key differences between the three protocols include:

• SPF confirms which servers can send emails on your behalf.
• DKIM adds a digital signature to your emails proving they aren’t altered after sending.
• DMARC ties SPF and DKIM together, setting up rules for how to handle authentication failures.

Proper setup of these protocols is critical to passing spam filters and improving inbox placement. For detailed configuration guides, read these MailReach’s expert blogs:

• How to Set Up DKIM
• How to Fix DMARC Failures
• Proper Setup of SPF and DKIM Records
  

Link Branding - The Overlooked Alignment Factor

Even with SPF and DKIM set up correctly, many SendGrid users fail authentication alignment because of Branded Links (formerly Link Branding). By default, SendGrid rewrites tracked links using its own domain (e.g., sendgrid.net), breaking DMARC alignment and reducing trust.

To fix this:

1. Go to Settings → Sender Authentication → Link Branding
2. Add and verify your custom subdomain, such as links.yourdomain.com
3. Update DNS with the CNAMEs SendGrid provides

This ensures that your click and open tracking links match your domain, not SendGrid’s, maintaining domain alignment and improving inbox placement.

2. Diagnose Spam Placement at the Source

The first step is to confirm where your SendGrid emails actually land and why. SendGrid’s “Delivered” status only confirms server acceptance, not inbox success. Run a few inbox placement tests (for example, with MailReach’s email spam test) or send directly to Gmail and Outlook to verify whether your emails reach the Primary, Promotions, or Spam folders.

Next, review your SendGrid event data for more insight.

• Deferred: The recipient’s server delayed delivery, often due to temporary reputation or rate-limit issues.
• Blocked: Delivery was refused entirely, usually indicating authentication or blocklist problems.
• Spam Report: Recipients flagged your email, showing user-level distrust that damages your sender reputation.

3. Avoid Spam Trigger Content

Even with perfect authentication and a good sender reputation, your emails may not reach inboxes if the content triggers spam filters. Certain elements raise red flags for mailbox providers like Gmail and Outlook. Avoid including:

• Links that use non-branded or third-party domains (such as sendgrid.net) which reduce trust alignment
• Too many clickable links or calls to action; limit to one clear next step
• Emails that are all images or image-heavy with little text, as filters struggle to interpret context
• Overloaded email signatures with excessive contact details, logos, or social icons that increase HTML size and reduce readability
• Use of URL shorteners, tracking pixels, or spam trigger words 

4. Warmup Your SendGrid IPs & Domains Properly

SendGrid is mainly designed for transactional and newsletter emails. These messages are expected by customers and usually get quick engagement. However, when SendGrid is used for B2B cold outreach, inbox providers treat these messages differently than transactional or newsletter emails. New domains or IPs with no history look suspicious without positive engagement signals.

SendGrid offers an internal warmup system that gradually increases your daily sending volume. This system gradually increases sending volume but does not directly affect engagement quality. Gmail and Outlook prioritize how recipients interact with your emails, such as opening, replying, and keeping messages in the inbox, over the sheer number of emails sent.

MailReach’s email warmup addresses this gap. It connects to real Google Workspace and Office 365 inboxes where messages receive human-like interactions. This includes opening, replying, marking as not spam, and archiving messages. Such interactions help mailbox providers trust your domain and IP faster.

A SendGrid warmup plan typically follows:

• Week 1–2: Send fewer than 50 emails daily, focusing on engagement through MailReach.
• Week 3–4: Gradually double volume every few days once open and reply rates are stable.
• Only move to full production sending once inbox placement is consistent and sender reputation is verified.

Note that B2C inboxes, SMTP relays, or custom servers do not influence how Gmail and Outlook perceive your domain’s trust. Warmup must occur within these ecosystems for best results.

5. Automate Inbox Placement and Spam Testing

Deliverability issues often go unnoticed until after a campaign launches. To avoid that, make inbox placement testing a mandatory pre-send step. This testing focuses on tracking exactly where your emails appear within major providers, rather than relying on outdated spam scores or keyword checks.

With MailReach’s email spam test, you can send a test campaign to a distributed network of real inboxes, each hosted on live domains and mail clients. The results show precise placement: inbox, promotions, or spam. It also identifies domain reputation issues, authentication gaps, and provider-specific filtering patterns.

Here’s how to build it into your workflow:

1. Send every new campaign or sequence to your MailReach test list
2. Analyze the inbox-to-spam ratio across providers
3. Flag authentication, content, or engagement issues for correction before sending live

6. Monitor Sender Reputation 

Your sender reputation determines whether mailbox providers trust your SendGrid emails or filter them as spam. Even with correct authentication, a weak reputation can limit inbox placement and reduce engagement.

Check for early warning signs in your SendGrid event logs, such as bounce spikes, deferred messages, or block listings that indicate providers are losing trust in your domain.

To track reputation more accurately, use MailReach’s Reputation Score, built specifically for B2B senders using professional inboxes like Google Workspace and Microsoft 365. It measures how engagement, bounce trends, and spam complaints affect your domain’s standing with major providers. A higher score means stronger sender reputation and better inbox placement across SendGrid campaigns.

7. Commit to Continuous Testing and Optimization

Deliverability remains stable only with consistent inbox placement testing, not with a one-time fix. Gmail and Outlook filters update regularly, requiring you to check your email patterns as often. Make it a standard practice in your SendGrid workflow to:

1. Conduct a spam placement test weekly or before each campaign to monitor inbox versus spam ratios across Gmail and Outlook
2. Track results over time to identify any reputation drops specific to providers
3. Modify sending behavior, pause high-bounce segments or slow send speeds if spam placement rises
4. Confirm improvements by retesting after each change

This ongoing process establishes a reliable system of continuous deliverability control, rather than relying on one-time audits. Monitoring real inbox outcomes, rather than relying on general engagement metrics, helps catch reputation declines early and keeps SendGrid domains performing consistently across major mailbox providers.

8. Use MailReach’s Warmup and Email Deliverability Solutions for SendGrid

MailReach strengthens SendGrid deliverability by improving your domain reputation outside SendGrid’s system. It works through inbox-to-inbox trust loops. Your messages interact with thousands of verified Gmail and Outlook accounts that behave like real users by opening, replying, and removing emails from spam. These natural engagement signals help mailbox providers learn to trust your domain and IP.

Here’s why it’s effective:

• Mailbox-level learning: Gmail and Outlook assign reputation at the domain level, rather than at the SendGrid IP level. Engagement from MailReach’s trusted inbox network engages with your messages, it strengthens that domain’s behavioral history within providers’ ecosystems.
• Real feedback loop: During warmup, MailReach detects technical issues, including failed SPF, DKIM, or DMARC alignment, and flags content-level risks such as heavy HTML or link mismatches.
• Simple SendGrid connection: You can integrate MailReach with SendGrid through SMTP credentials or an API key in minutes (see how to connect SendGrid SMTP to MailReach).

Combining SendGrid’s infrastructure with MailReach’s engagement-driven signals establishes lasting domain credibility with major mailbox providers. This approach converts temporary deliverability fixes into sustainable inbox success.

9. Manage Suppression Lists and Bounce Handling Effectively

Strong deliverability depends on how cleanly you manage your SendGrid suppression data. Every bounce or complaint sends a negative signal to mailbox providers, so staying on top of these events protects both domain and IP reputation.

SendGrid automatically suppresses hard bounces and spam complaints, preventing retries to invalid or complaining addresses. However, soft bounces and temporary errors like full inboxes or transient connection issues aren’t handled automatically. These must be monitored and cleaned manually to prevent them from accumulating and signaling poor list hygiene.

Follow this repeatable process:

1. Regularly review the Suppression Management section in SendGrid for bounce types
2. Remove repeated soft bounces (three or more occurrences) from active lists
3. Sync suppression data with your CRM to avoid accidental re-sends
4. Track deliverability metrics before and after removals to confirm positive impact

Proactively managing suppression lists ensures you send only to responsive, trusted recipients and maintain your domain reputation across Gmail, Outlook, and other major providers.

Achieve Consistent Inbox Placement with SendGrid

Strong email deliverability results from consistently focusing on authentication, sender reputation and email content. Every aspect of your email program, from DNS alignment to content strategy, affects how mailbox providers evaluate your domain.

Combining SendGrid’s reliable infrastructure with MailReach’s inbox-level intelligence helps you identify issues early, build sender trust, and maintain steady inbox placement across Gmail, Outlook, and other major platforms.

Ongoing testing, precise warmup strategies, and effective suppression management make deliverability a reliable, repeatable process. With the right systems in place, each SendGrid email becomes an opportunity to strengthen trust and protect your brand reputation.

Connect SendGrid to MailReach and keep your emails in the inbox. Click here.