Want your emails to land in inboxes instead of spam folders? Email deliverability is key. It ensures your messages reach your audience’s primary inbox, not spam or promotions. Here’s how you can improve it:
Keeping track of key metrics and setting up domain authentication are essential steps to ensure your emails land in inboxes rather than getting lost in spam folders. Metrics help you identify areas to improve, while domain authentication confirms your emails are legitimate.
Inbox Placement Rate reflects the percentage of emails that make it to the primary inbox instead of spam or other folders. A strong placement rate is above 90%, with some industries reaching as high as 98%. If your rate dips below 90%, it’s time to dig into potential issues.
Bounce Rate measures emails that fail to deliver. Hard bounces occur when an email address is invalid, while soft bounces happen due to temporary problems like full inboxes. Aim to keep your bounce rate at or below 0.3%.
Spam Rate tracks how many emails are flagged as junk by mailbox providers. Google advises keeping this rate under 0.1%, with an ideal target of less than 0.03%. This is different from the spam complaint rate, which measures when recipients manually mark emails as spam.
Engagement Metrics - like open rates, click rates, and replies - are indicators of how much recipients value your emails. Low engagement or sudden increases in unsubscribes can signal issues with your content or how often you’re sending emails.
Domain and IP Reputation scores represent how mailbox providers view your sending behavior over time. These scores take into account your authentication setup and how recipients interact with your emails. A low reputation can send even well-written emails straight to spam.
"Email deliverability is a measure of the health of your email marketing program, so it's important to do regular check-ups on your domain, IP, and authentication in particular to make sure you're up-to-date, just like how we all go to the doctor each year."
– Carin Slater, Manager of Lifecycle Email Marketing at Litmus
By understanding these metrics, you can take steps to strengthen your email deliverability - and domain authentication plays a big role in that.
To confirm your emails are coming from your domain, you’ll need to configure SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance).
"SPF, DKIM, and DMARC help authenticate email senders by verifying that the emails came from the domain that they claim to be from."
– Cloudflare
Setting these up usually means adding TXT records to your domain’s DNS settings. Afterward, verify them using tools like MXToolbox. Services like Warmforge also offer deliverability checks to ensure everything is working smoothly, catching errors that could harm your email performance.
"Protocols like SPF, DKIM, and DMARC act as virtual guards, verifying sender identity and content integrity to ward off spam threats and build an impenetrable cold email infrastructure."
– Carlos Ascanio
Once authentication is in place, warm up your email domain gradually to establish a strong reputation with mailbox providers. Together, accurate metrics and proper authentication form the foundation of a reliable email outreach strategy.
Up next, explore tools that can further refine and test these deliverability essentials.
The right tools can mean the difference between emails landing in inboxes or vanishing into spam folders. With 70% of emails showing at least one spam-related issue and 22% of email marketers skipping deliverability measurements, having reliable tools is essential for success. Below, we break down some of the top tools, their features, pricing, and what they’re best suited for.
Warmforge is an AI-powered email warm-up tool designed to improve inbox placement through simulated engagement. It’s highly rated, with a 4.9/5 on G2 and 4.8/5 on Product Hunt. For example, a SaaS startup improved inbox placement from 54% to 93% in just two weeks, while a digital agency cut spam complaints by 50%. Warmforge offers automated warm-up, deliverability monitoring, placement tests, and DNS/MX health checks. Pricing starts at $12 per mailbox per month, with bulk discounts bringing it down to $3 per mailbox per month.
GlockApps focuses on inbox placement monitoring, spam testing, and authentication checks. It offers a free plan with 2 spam test credits and up to 10,000 DMARC checks per month. The Essential plan costs $59/month and includes 360 spam test credits and 600,000 DMARC checks. Reviews are mixed, with a 3.7/5 rating on G2 but a higher 4.8/5 on Capterra.
Mailtrap is geared toward pre-send diagnostics and content analysis. Its free plan supports 100 emails and one inbox, while paid plans start at $14.99/month for 5,000 emails and five inboxes. It consistently earns a 4.8/5 rating for its developer-friendly features.
ZeroBounce specializes in email list validation and deliverability testing. Plans for email verification start at $18/month for 2,000 credits. The platform also provides a free toolkit with 1 inbox test, 1 email server test, and blacklist monitoring. It maintains strong user satisfaction with a 4.7/5 rating on G2.
MXToolbox focuses on email and network diagnostics. Their Delivery Center plan starts at $129/month for monitoring up to 5 domains and 500,000 email messages. The Plus version, which includes advanced threat tools, costs $399/month and supports up to 5 million messages.
Folderly automates mailbox warming and campaign engagement. Plans start at $96 per mailbox per month, with discounts for larger volumes. The platform boasts a 4.8/5 rating on G2 and includes their Inbox Insights add-on for free with 2 monthly tests.
| Tool | Primary Focus | Starting Price | Key Strengths | G2 Rating | Best For |
|---|---|---|---|---|---|
| Warmforge | AI warm-up | $3-$12/mailbox/month | Engagement simulation, health checks | 4.9/5 | Cold outreach, bulk operations |
| GlockApps | Inbox placement testing | $59/month | Authentication checks, spam testing | 3.7/5 | Technical deliverability analysis |
| Mailtrap | Pre-send diagnostics | Free-$14.99/month | Email debugging, content analysis | 4.8/5 | Developers, testing environments |
| ZeroBounce | List validation + testing | $18/month | Email verification, toolkit | 4.7/5 | List hygiene, verification |
| MXToolbox | DNS and network diagnostics | $129/month | DNS monitoring, technical analysis | 4.0/5 | IT teams, infrastructure monitoring |
| Folderly | Automated warming | $96/mailbox/month | Tracking and detailed reports | 4.8/5 | High-stakes campaigns |
When deciding on a tool, it’s important to match your needs with your budget. Warmforge stands out as a cost-effective option for businesses focused on cold outreach, especially with its bulk pricing. Mailtrap is ideal for developers who need pre-send testing, while ZeroBounce is perfect for ensuring your email lists are clean and up-to-date. For enterprises requiring detailed analytics and reporting, Folderly is a strong choice.
Combining tools often yields the best results. For instance, using a pre-send testing tool like Mailtrap alongside a warm-up service like Warmforge, and then monitoring performance with placement testing tools, ensures a comprehensive approach. This way, you can optimize everything - from content quality to sender reputation.
Ensuring your emails land in inboxes instead of spam folders requires a structured approach. This three-step process focuses on identifying and resolving deliverability issues, covering technical setup, content quality, and ongoing performance monitoring.
Validating your domain is the first step to avoid spam filters. Most email providers require proper authentication, including SPF, DKIM, and DMARC records.
v=spf1 include:_spf.example.com ~all
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com
Once authentication is in place, move on to testing email placement and identifying potential spam triggers.
After authenticating your domain, the next step is to ensure your emails reach inboxes consistently. Placement tests show where your emails land - primary inbox, spam, or promotions - while spam tests identify problematic content that could trigger filters.
Warmforge allows one free placement test per month, helping you monitor inbox placement across major providers like Gmail, Outlook, and Yahoo. For frequent testing, tools like GlockApps offer 2 free spam test credits monthly or an Essential plan at $59/month for 360 credits.
"GlockApps provides in-depth diagnostics to help pinpoint the exact cause and provides specific actions to resolve it. It goes beyond surface-level checks and really dives into technical details like DNS settings, content triggers, and blacklist monitoring." - Praduman Singh, Senior Sales Development Representative at Zimetrics
When running tests, focus on spam scores and content analysis. Tools like Mailtrap excel at pre-send diagnostics, catching issues before launch. Their free plan supports 100 emails and one inbox, with paid plans starting at $14.99/month for higher volumes. Pay attention to common spam triggers, such as excessive capitalization, too many links, suspicious attachments, or overly promotional language. For example, replacing "FREE" with alternatives like "complimentary" or "no cost" can reduce spam scores.
Experiment with small changes in subject lines, content length, or sender names to improve performance. While seed lists provide valuable insights, real engagement metrics from your actual audience give a more accurate picture of deliverability. Use seed list results as a starting point and validate findings with campaign data.
Ongoing monitoring is essential to keep your deliverability on track, as it can fluctuate based on sending habits, content, and recipient engagement. Pay close attention to key metrics like bounce rates, engagement levels, and blacklist statuses.
Set up automated alerts for critical metrics. Many ESPs allow notifications for sudden spikes in bounce rates or drops in engagement, enabling you to act quickly. Instead of reacting to daily changes, review metrics weekly to identify long-term trends. Document any adjustments to your strategy - this historical data will be invaluable for troubleshooting and optimizing your email campaigns over time.
Keeping your emails out of the spam folder is critical for maintaining your sender reputation and ensuring your campaigns perform well. With 347 billion emails sent daily - and nearly half flagged as spam - even legitimate senders face challenges from increasingly strict email provider standards. Building on earlier discussions about metrics and authentication, this section covers how to identify and resolve deliverability issues and improve your results.
Authentication Failures: Misconfigured SPF, DKIM, or DMARC records are a common cause of spam flags or outright blocks. With Gmail, Yahoo, and Microsoft tightening their requirements in 2025, proper setup is more important than ever. Many senders only realize their authentication is incomplete after noticing a sudden drop in inbox placement.
High Bounce Rates: A bounce rate over 5% often signals outdated contact lists or poor acquisition practices. Hard bounces - caused by invalid email addresses - hurt your reputation much more than soft bounces, which result from temporary server issues.
Spam Complaints: Industry standards recommend keeping spam complaint rates below 0.1% (1 complaint per 1,000 emails). However, some B2B campaigns report rates exceeding 2%. Providers typically flag campaigns with complaint rates higher than 0.3%, which can lead to automatic filters and reduced deliverability.
Blacklisting: Landing on a major blacklist, such as Spamhaus or Barracuda, can block your emails entirely. Blacklisting often results from spam complaints, authentication failures, or sending emails to spam traps. Unlike gradual issues, blacklisting can disrupt your email program overnight.
Poor Sender Reputation: Low engagement, high complaints, and inconsistent sending patterns can damage your sender reputation over time. Email providers track these metrics closely, and recovering a tarnished reputation may take months. Addressing these issues requires focused, systematic efforts.
The best way to troubleshoot depends on the issue at hand. For example, fixing authentication can provide quick technical relief, while improving sender reputation through practices like automated warm-ups takes time. Blacklisting demands immediate attention, but long-term success relies on continuously refining your technical setup, email content, and list management. Combining these methods ensures a balanced approach to improving deliverability.
Email deliverability plays a critical role in the success of marketing campaigns. With statistics showing that 1 in 7 marketing emails fails to reach the inbox and an average deliverability rate of 81% across campaigns, keeping a close eye on performance is not just helpful - it’s essential. Consistent monitoring ensures you maintain strong communication with your audience.
Key practices like proper authentication, tracking metrics such as bounce rates and spam complaints, and leveraging testing tools can help identify and address issues before they impact your campaigns.
"Deliverability is a measure of the health of your email marketing program, so it's important to do regular check-ups on your domain, IP, and authentication in particular to make sure you're up-to-date, just like how we all go to the doctor each year".
The payoff for diligent deliverability monitoring is clear. Marketers who regularly track deliverability see better results - successful email marketers monitor deliverability 22% more often. And considering that email marketing boasts an impressive 4,400% ROI, with $44 generated for every $1 spent, these efforts are well worth it.
Using tools designed to improve deliverability can take your campaigns even further. For example, Warmforge simplifies cold outreach by automating email warm-up and providing continuous deliverability monitoring. Its AI-driven features have delivered tangible results, like helping a SaaS startup boost inbox placement from 54% to 93% in just two weeks. With pricing starting at $10 per month and a heat score system that removes the guesswork from campaign launches, Warmforge offers a straightforward way to maintain a strong sender reputation.
SPF, DKIM, and DMARC are key email authentication tools designed to build trust in your emails and ensure they land in your recipients' inboxes. Together, they verify that your messages come from a legitimate source, protect against spoofing attempts, and help avoid being flagged as spam.
Properly implementing these protocols reduces the risk of your emails being blocked or flagged as spam, improving deliverability and ensuring your messages reach the right audience.
To ensure your emails consistently reach your audience's inboxes, it's crucial to keep an eye on a few essential metrics:
By regularly reviewing these metrics, you can quickly spot and address potential issues, ensuring your emails consistently reach their intended audience.
To get your domain off to a strong start and build a solid sender reputation, begin by sending a small number of emails - around 100 to 500 per day - to your most engaged contacts. These are the people who have recently opened or clicked on your emails. Over time, slowly increase the number of emails you send daily by 20–50% each week, keeping your sending patterns steady and prioritizing high engagement.
Stick to active subscribers initially and steer clear of inactive or unengaged contacts during this phase. This gradual approach helps you earn trust with mailbox providers, lowers the chances of your emails being marked as spam, and boosts your deliverability rates.