Boost your email deliverability by focusing on data source quality. This guide covers technical authentication, list hygiene, and monitoring with vendor.

Improving email deliverability starts with the data source. While technical setups like DMARC are crucial, data providers for local SMBs show deliverability rates below 70%, a gap incumbents like Apollo and ZoomInfo struggle to fill. A data-first methodology, focusing on verified, directory-sourced contacts and per-lead bounce credits, provides a more reliable foundation than AI-scored lists.

TL;DR

Properly configured DMARC policies have been required by Gmail and Yahoo for bulk senders since February 2024 to avoid spam placement.
Data sourced from public directories for local businesses can yield over 70% verified deliverable emails, a segment where scaled B2B databases are structurally weak.
B2B email lists decay at an average rate of 22.5% per year, requiring continuous hygiene beyond a one-time verification check.
Inbox placement tools like GlockApps report that 15% of authenticated emails still miss the primary inbox globally.
A hard bounce rate above 2% is a red flag for ISPs; a rate above 5% can lead to blacklisting.

How Do SPF, DKIM, and DMARC Reduce Spam Folder Placement?

Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC) form a foundational triad for email authentication, directly influencing whether an email reaches the inbox or the spam folder. Since February 2024, Google and Yahoo have mandated that bulk senders, defined as those sending over 5,000 emails per day, must have at least a basic DMARC policy (p=none) published. This requirement was a direct response to the rising tide of spam and phishing, which leverages unauthenticated domains. The mandate spurred a massive wave of adoption; in the first 60 days of 2024, 2.5 million domains implemented new authentication records. However, this initial compliance often stops short of providing real protection. Data from Valimail's 2026 State of DMARC Report reveals a significant "Enforcement Gap," with DMARC awareness reaching 78% but actual enforcement via p=quarantine or p=reject policies plateauing at just 42%. This gap means a majority of domains that are technically compliant remain vulnerable to spoofing, a risk that proper data sourcing and authentication can mitigate.

SPF records are crucial for deliverability but come with a significant technical constraint: a limit of 10 DNS lookups per validation. Exceeding this limit results in a PermError, which receiving mail servers often treat as an outright SPF failure, leading to deliverability issues or outright rejection. This limitation is frequently encountered by organizations using multiple third-party services for functions like marketing automation, CRM, and support ticketing, as each service typically adds an include statement to the SPF record. A 2026 study by DMARCguard analyzing 5.5 million domains found that 4.8% of all domains with an SPF record were in violation of the 10-lookup limit, creating self-inflicted delivery failures. To avoid this, senders must regularly audit their SPF records, remove entries for unused vendors, and explore techniques like creating specific subdomains for different email streams or using automated SPF flattening services to how to improve email deliverability. Mismanaging SPF records not only undermines authentication but also directly harms sender reputation.

While SPF validates sending servers, DKIM provides message integrity through cryptographic signatures, and its effectiveness depends on disciplined key management. Security best practices, echoed by major email providers, recommend rotating DKIM keys every 3 to 6 months to mitigate the risk of a compromised key being used for forgery. A long-lived key provides a larger window for attackers to exploit a breach and send fraudulent emails that appear to be from a legitimate domain. The rotation process involves publishing a new public key in DNS under a new selector, running both the old and new keys in parallel for a transition period of at least a week, and then retiring the old key after confirming the new one is signing correctly. Although DKIM key rotation itself does not directly reset or improve sender reputation, a poorly executed rotation can cause signature mismatches and DMARC failures, leading to a decline in inbox placement. Using strong 2048-bit keys is now the standard, as keys under 1024 bits are often treated as a failed signature by receivers.

DMARC unifies SPF and DKIM, providing a mechanism for both enforcement and feedback, which is critical for improving deliverability over time. While the February 2024 mandates from Google and Yahoo only required a p=none policy, this setting is purely for monitoring and offers no protection against spoofing. The real value of DMARC is realized with enforcement policies like p=quarantine or p=reject. These policies instruct receiving servers to either sideline or block messages that fail authentication, directly preventing domain abuse. More importantly, they generate actionable feedback through aggregate (RUA) and forensic (RUF) reports. These XML reports, while difficult to read manually, provide detailed data on which services are sending on your behalf and whether they are passing or failing authentication. Commercial services like Dmarcian and Valimail, as well as open-source tools like parsedmarc, are designed to parse these reports into human-readable dashboards, enabling teams to identify misconfigurations and unauthorized senders. This feedback loop is essential for safely moving from a monitoring policy to a full enforcement policy, which is the ultimate goal for securing a domain and maximizing deliverability.

DMARC Policy	Protection Level	Action on Failed Emails	Reporting Capability	Recommended Use Case
`p=none`	None (Monitoring Only)	No action taken by the receiver; email is delivered.	Full (RUA/RUF reports are generated)	Initial setup phase for discovery and auditing of email sources without impacting mail flow.
`p=quarantine` (pct=10)	Low (Partial Enforcement)	10% of failing emails are sent to spam/junk folder; 90% are delivered.	Full (RUA/RUF reports are generated)	Gradual rollout phase to test the impact of quarantine on a small percentage of mail.
`p=quarantine` (pct=100)	Medium (Full Quarantine)	All failing emails are sent to the recipient's spam/junk folder.	Full (RUA/RUF reports are generated)	For organizations that want to prevent spoofed emails from reaching the inbox but are not yet confident in rejecting them outright.
`p=reject` (pct=10)	Medium (Partial Enforcement)	10% of failing emails are blocked entirely; 90% are delivered.	Full (RUA/RUF reports are generated)	Final testing phase before full enforcement to ensure no legitimate mail is being rejected.
`p=reject` (pct=100)	High (Full Enforcement)	All failing emails are blocked and not delivered.	Full (RUA/RUF reports are generated)	The end goal for complete domain protection, preventing all unauthorized use of the email domain.

Why Data Source Quality Is the Primary Limiter on Deliverability

Large B2B data aggregators, including prominent names like ZoomInfo and Apollo.io, often exhibit lower contact accuracy for small and medium-sized businesses (SMBs) compared to their enterprise-level counterparts. While these platforms provide immense breadth, their accuracy for smaller, less digitally prominent companies can be a significant limiter on email deliverability. For instance, one 2026 benchmark test on 1,000 leads found Apollo's email accuracy to be 78% and ZoomInfo's to be 84%, which still leaves a considerable margin for bounces that can damage a sender's reputation. Another analysis noted that while ZoomInfo excels with enterprise data, its coverage of small businesses is a known gap, a segment where Apollo.io is often considered stronger, though still imperfect. This accuracy gap is compounded by the fact that most B2B data providers deliver only 50% accuracy on average, despite marketing claims of 95% or higher. For SMBs, whose contact information is less stable and public, this means that relying on large, generalized databases can result in deliverability rates far below the acceptable threshold, directly impacting campaign viability before a single email is even sent.

The inherent decay of contact information is a primary factor degrading email deliverability, with B2B email lists decaying at an average rate of 22.5% annually. This means that a static list of 10,000 contacts will contain at least 2,250 invalid addresses after just one year, a figure that can climb to over 35% in fast-moving industries. The 'Email Decay Report for 2025' from ZeroBounce noted an even higher degradation rate of 28% per year, having detected 2.5 billion invalid email addresses in 2024 alone. This constant data erosion, driven by job changes, company mergers, and technology migrations, directly translates into higher bounce rates, which damages sender reputation and can lead to blocklisting by providers like Google who enforce a hard bounce rate below 2%. The financial impact is significant; Gartner research from 2020 estimated that poor data quality costs organizations an average of $12.9 million annually, a cost largely driven by wasted marketing efforts and lost sales opportunities from unreliable data. A data-first approach, therefore, requires continuous verification, not just a one-time purchase of a list that becomes a depreciating asset the moment it is downloaded.

A crucial distinction exists between a 'verified' email checkmark and a transparent deliverability percentage, a difference that significantly impacts campaign outcomes. Many providers' 'verified' status simply confirms that an email address has the correct syntax (e.g., name@domain.com) and that the domain has valid MX records, a process known as email validation. However, this does not confirm the mailbox actually exists or can receive mail. True email verification goes a step further by pinging the mail server to confirm the specific inbox is active. This is why a list can be fully 'validated' yet still produce high bounce rates. Providers that offer a real deliverability percentage on each lead, or offer per-lead bounce credits, provide a much stronger guarantee. For example, some high-quality data providers can achieve deliverability over 90%, with hard bounce rates below 1%, by using multi-source waterfall enrichment and real-time verification at the moment of export. In contrast, single-source databases often struggle to surpass 62% valid emails in testing, highlighting the performance gap between a simple checkmark and a methodologically sound deliverability guarantee.

Advanced List Hygiene: Moving Beyond Simple Verification

Standard SMTP verification tools are fundamentally incapable of validating email addresses on catch-all domains, which creates a significant blind spot in list hygiene. A catch-all server is configured to accept all incoming mail for a domain, regardless of whether the specific mailbox exists, rendering the typical verification handshake useless. Research from Orbisearch's 2026 "State of Catch-All Domains" report, which analyzed 1.6 million business domains, found that 31.4% were configured as catch-all. Other analyses suggest this figure can be as high as 40-60% for certain B2B lists. When a verification tool probes a catch-all server, the server returns a positive "250 OK" response for any address, including nonexistent ones like "[email protected]". This forces most verification services to label these addresses as 'risky' or 'unknown,' leaving the sender to either discard a large portion of their list or risk sending to invalid addresses that will hard bounce. Sending to these unverified catch-all addresses is a direct cause of inflated bounce rates; a campaign sent to a list where 30% of addresses are unverified catch-alls can easily exceed the 2% hard bounce threshold that damages sender reputation. This technical limitation means that true list hygiene requires a more advanced method than simple SMTP checks to resolve the validity of a substantial part of any given B2B contact list.

Adopting a bounce-processing system that automatically credits an account for hard bounces aligns financial incentives with the data provider, shifting the risk of poor data quality away from the email sender. Traditional list verification services charge on a per-check or credit basis, a model where the vendor profits regardless of whether the verified email actually reaches an inbox. This creates a scenario where a sender pays to clean a list but still suffers the reputational damage and financial loss from hard bounces. In contrast, a data-first model, such as one offering per-lead bounce credits, ensures the provider is only compensated for deliverable contacts. This approach is critical given that B2B email lists decay at a rate of 22.5-30% annually, meaning a static list is a depreciating asset. Research from GetResponse's 2024 Email Marketing Benchmarks report, analyzing 4.4 billion messages, identified an average bounce rate of 2.33%, a figure that can quickly escalate with purchased lists and damage sender reputation. By using a provider that guarantees deliverability with bounce credits, marketers are protected from the financial and reputational costs of bad data, such as those detailed in the Belkins guide to improving email deliverability. This model transforms verification from a transactional cost center into a performance-based partnership.

Segmenting email lists based on historical engagement is a proven method for increasing inbox placement, as mailbox providers interpret positive interactions as a primary signal of wanted mail. Providers like Gmail and Microsoft Outlook use sophisticated algorithms that track whether recipients open, click, reply to, or forward messages from a specific sender. This data forms a behavioral reputation score for the sending domain; high engagement reinforces trust, while low engagement can cause future campaigns to be filtered directly to spam, even for authenticated mail. According to a 2025 Mailchimp analysis, segmented campaigns earn 14.31% higher open rates and over 100% higher click rates compared to non-segmented sends. This lift in engagement directly translates to improved deliverability. A HubSpot research report from 2026 found that marketers see 30% more opens from segmented campaigns, creating a virtuous cycle where higher engagement improves sender reputation, which in turn leads to better inbox placement and even more engagement. By isolating and targeting the most active contacts, such as those who have opened an email in the last 30 or 60 days, senders can ensure their most critical messages are sent to a receptive audience, generating the positive signals needed to improve deliverability for the entire list over time.

Real-time verification APIs from services like ZeroBounce and NeverBounce provide an essential layer of list hygiene, but they cannot guarantee inbox placement, only that an email address is syntactically correct and exists at the server level. These tools perform a multi-step validation process, including SMTP handshakes and checks against known databases of disposable or high-risk domains, to confirm an address is valid at the moment of the query. ZeroBounce, for instance, guarantees 99.6% accuracy in identifying valid addresses, while NeverBounce guarantees a bounce rate of no more than 3% for verified contacts. However, this verification of validity is distinct from the concept of deliverability, which is whether a message is accepted by the server, and inbox placement, which is whether the message avoids the spam folder. According to Validity's 2024 Email Deliverability Benchmark, approximately one in six legitimate, permission-based emails never reaches the inbox, highlighting the gap between a valid address and a visible message. Mailbox providers make filtering decisions based on a sender's reputation and recipient engagement signals, factors that a real-time validity check does not measure. Therefore, while tools like those mentioned in the Belkins deliverability guide are crucial for minimizing hard bounces, they are only the first step in a comprehensive deliverability strategy.

Does Your Sending Infrastructure Pass the Mailbox Provider Test?

Warming a new IP address must follow a disciplined, gradual volume increase to build a positive sender reputation with mailbox providers. A common and effective methodology involves starting with a low volume, typically 50-100 emails on day one, and progressively increasing this amount over several weeks. A widely adopted schedule is to double the sending volume every 3-4 days, but only if engagement metrics remain positive. This process, which can take anywhere from two to eight weeks, allows Internet Service Providers (ISPs) like Gmail and Outlook to recognize and evaluate your sending patterns without flagging you as a potential spammer. The initial sends should target your most engaged subscribers, such as those who have opened or clicked an email in the last 30 days, as their positive interaction signals to ISPs that your mail is wanted. Abruptly sending high volumes from a 'cold' IP is one of the fastest ways to damage your reputation, leading to throttling, blocklisting, or having your messages routed directly to the spam folder. Because most ISPs only retain reputation data for about 30 days, any IP that has been inactive for a month or more must be warmed up again from scratch.

Choosing between a shared IP pool and a dedicated IP is a critical infrastructure decision based on volume, budget, and control. Shared IP pools, where multiple senders use the same IP addresses, are highly cost-effective and are typically included in the base price of an email service provider's plan. This makes them ideal for low-to-moderate volume senders. However, the key drawback is shared reputation; the poor sending practices of one user can negatively impact the deliverability of everyone in the pool. Conversely, a dedicated IP gives a sender exclusive control over their reputation but comes at a higher cost and requires more management. Providers like Amazon SES offer dedicated IPs starting at $24.95 per month, while MailerSend and Postmark price theirs around $50 per month. SendGrid's Pro plan, starting at $89.95 per month as of October 2026, includes a dedicated IP, which is often the primary reason users upgrade from lower tiers. A dedicated IP is generally recommended for businesses sending over 100,000 emails per month, as it isolates their reputation and provides the stable foundation needed for a systematic IP warming process.

Beyond IP reputation, using a custom tracking domain is essential for maintaining control over engagement tracking and deliverability. When you track opens and clicks, sending platforms insert tracking links that often use a default, shared domain. This is a significant risk, as a single bad actor on the platform can get that shared domain blocklisted, immediately damaging the deliverability of all other users. Setting up a custom tracking domain, such as track.yourcompany.com, aligns your tracking links with your sending domain, which improves trust with both recipients and spam filters. This is a critical step detailed in many guides on how to improve email deliverability. Equally important is monitoring recipient feedback through Feedback Loops (FBLs). Major mailbox providers, including Microsoft and Yahoo, offer FBLs that send reports when a recipient marks your email as spam. This data is vital for managing your sender reputation, as the industry-standard threshold for spam complaints is extremely low, often cited as 0.1% to 0.3%. Exceeding this rate signals to providers that your mail is unwanted, leading them to filter your future campaigns to the spam folder.

Provider	Dedicated IP Plan	Monthly Price (as of Oct 2026)	Volume Requirement	Ideal Use Case
Amazon SES	Standard Dedicated IP	$24.95 per IP	None, but recommended for >100k emails/day	Technical teams wanting maximum cost savings at high volume.
SendGrid	Email API Pro Plan	Starts at $89.95 (includes 1 IP)	None, plan starts at 100k emails/month	Growing businesses needing an all-in-one solution with a dedicated IP included.
Postmark	Dedicated IP Add-on	$50.00 per IP	300,000+ emails per month	High-volume senders focused purely on transactional email deliverability.
MailerSend	Dedicated IP Add-on	$50.00 per IP	500,000+ emails per month	High-volume senders on Professional or Enterprise plans needing reputation control.
HubSpot	Dedicated IP Add-on	$300.00	Available on Professional or Enterprise plans	Marketing teams using the HubSpot ecosystem for all campaigns.

How Content Choices and Engagement Signals Impact Spam Filters

Plain-text emails can achieve significantly higher engagement in B2B contexts because they appear more personal and contain less complex code for spam filters to scrutinize. While many marketers gravitate towards heavily branded HTML templates, research consistently shows that simpler is often better for deliverability and action. For instance, a HubSpot analysis found that plain-text emails receive 42% more clicks than HTML formats. This performance gap exists because a plain-text message feels like a one-to-one communication from a colleague, not a mass marketing broadcast. When a recipient sees a polished design, they immediately recognize it as a commercial message, which can lower engagement. Furthermore, from a technical standpoint, complex HTML can be a red flag. According to a 2026 deliverability study, over 45% of HTML emails were found to be malicious, prompting high-security organizations to automatically block them or strip their formatting. This reality, combined with the fact that plain-text emails show 21% higher click-to-open rates, makes a strong case for prioritizing simple, text-based communication in any serious outreach strategy.

Using common URL shorteners can severely damage email deliverability because these tools are frequently exploited in phishing and spam campaigns, making them a major red flag for inbox providers. Services like Bitly obscure the final destination of a link, and filters from providers like Gmail and Outlook treat this lack of transparency as a risk factor. Because spammers use shorteners to hide malicious sites, filters are trained to view the shorteners themselves with suspicion, regardless of the sender's intent. According to a Spamhaus advisory updated in Q3 2026, domains associated with public URL shorteners are often added to blocklists due to their use in fraudulent activities, meaning a legitimate email can be penalized due to the poor reputation of a shared resource. This creates a situation where even a perfectly safe link can harm your content score and cause the message to land in the spam folder, simply because the path was obscured. For this reason, it is always recommended to use full, direct destination links to maintain transparency and trust with both recipients and their mailbox providers, as detailed in Belkins' 2026 deliverability guide.

Personalization tokens that fail to populate, such as displaying 'Hi {first_name},' are a powerful negative signal to both recipients and spam filters, often leading to increased spam complaints and long-term reputation damage. This error instantly breaks the illusion of a personal, one-to-one message, signaling to the recipient that they are just a line item in a poorly managed database. The impact is more than just cosmetic; raw code in the email body is a clear red flag for spam filters, which often interpret it as a sign of a malformed or potentially malicious message. This can lead to deliverability drops of 40-50% for the affected campaign and harm the sender's domain reputation for weeks. A 2024 analysis of common personalization failures noted that this issue is frequently caused by incomplete underlying data, where a property like 'first name' is populated for only a fraction of the contact list. This type of error, which reveals the automation behind the message, is more jarring than sending a generic greeting and actively works against the goal of building trust.

Asking a direct question to encourage a reply is one of the most powerful positive engagement signals a sender can generate, directly improving their reputation with major mailbox providers like Gmail and Outlook. Unlike passive opens, which have become unreliable due to Apple's Mail Privacy Protection, a reply is a conscious and unambiguous action from the recipient. It tells the provider that the email was not only wanted but was relevant and valuable enough to warrant a response. Mailbox providers track these interactions closely, using reply rates as a strong indicator of a sender's quality and the health of their list. A steady stream of replies helps build domain reputation, signaling that a real relationship exists between the sender and the audience. This positive feedback loop leads to better inbox placement for future campaigns. Conversely, low reply volume, especially when combined with high bounce rates, is a clear red flag that the content is not resonating, which can cause providers to route future messages to spam. As noted in the Salesforce "State of Sales 5th Edition" report, which surveyed over 7,700 professionals, building genuine connections is paramount, and a conversational approach that invites a response is a key part of that strategy.

How to Audit and Monitor Deliverability With Precision

Precision in deliverability starts with measuring exactly where your emails land. Inbox placement tests, available from services like GlockApps or Mail-tester.com, provide the necessary diagnostic data by sending messages to a seed list of real mailboxes at major providers and reporting the outcome. These tests reveal the percentage of emails that reach the primary inbox, get routed to spam, or go missing entirely. According to Validity's 2025 Email Deliverability Benchmark, which analyzed billions of email sends, the global inbox placement rate was 83.5% in 2024, meaning roughly one in six legitimate marketing emails never reached the primary inbox. This figure highlights a significant gap between 'delivered' and 'inboxed'. For B2B senders, performance can vary dramatically by provider; the same report noted that Microsoft's inbox placement was only 75.6%, whereas Gmail's was a higher 87.2%. Auditing this metric provides a baseline to measure improvement and identifies which specific mailbox providers are causing the most significant delivery challenges, allowing for a more targeted and effective remediation strategy.

Analyzing DMARC aggregate reports (RUA) is a critical, non-negotiable step for identifying and stopping unauthorized use of your sending domain. These XML reports, sent by receiving mail servers, provide a summary of all messages sent purporting to be from your domain, detailing which ones passed or failed SPF and DKIM authentication. By parsing these reports with a tool like dmarcian or EasyDMARC, you can pinpoint the IP addresses of every server sending mail on your behalf. This process quickly uncovers unauthorized third-party services or, worse, malicious actors spoofing your domain to phish customers, which directly damages your sender reputation. According to Litmus's 2026 guide on DMARC analysis, the primary goal is to identify legitimate but misconfigured email sources and detect unauthorized senders. For example, if a marketing automation platform you no longer use still appears in your RUA reports, it signals a lingering security risk. Systematically reviewing these reports, as detailed in resources like Belkins's guide to improving email deliverability, allows you to enforce a strict DMARC policy (p=reject) with confidence, ensuring only authenticated mail reaches its destination and protecting your brand's integrity.

Monitoring your hard bounce rate is essential, as a rate consistently above 2% serves as a major red flag to Internet Service Providers (ISPs) and can precipitate blocklisting. Hard bounces are permanent delivery failures, and a high rate signals to providers like Gmail and Outlook that your organization engages in poor list hygiene, a behavior pattern indistinguishable from that of spammers. While the industry-accepted threshold is 2%, many experts recommend aiming for a hard bounce rate below 0.5% to maintain a healthy sender reputation. It is crucial to distinguish between hard and soft bounces by their SMTP response codes. Soft bounces, which generate 4xx codes (e.g., 421, 450), indicate temporary issues such as a full mailbox or a server that is temporarily unavailable; these messages can often be retried. In contrast, hard bounces produce 5xx codes (e.g., 550, 553), which signify a permanent failure like an invalid address or a non-existent domain. As defined in RFC 5321, a 5xx response means the sender should not repeat the request, making immediate suppression of these addresses from all future sends a mandatory practice to protect your sender score.

Frequently Asked Questions

What is a good email deliverability rate?

A good email deliverability rate is over 98%, but top performers aim for an inbox placement rate of 95% or higher. While a 99% delivery rate means your emails did not bounce, inbox placement measures how many actually reached the primary inbox, which is the more meaningful metric. According to Validity's 2024 benchmark, roughly one in six emails fails to reach the inbox, making rates below 85% a clear sign of underlying issues with your list or reputation. Consistently falling below this threshold signals to providers like Gmail that your sending practices are poor, increasing the likelihood of future emails going to spam.

How do I fix my emails going to spam?

Fixing emails going to spam starts with authenticating your sending domain using SPF, DKIM, and DMARC. These technical records prove to receiving servers that your mail is legitimate, a requirement enforced by Google and Yahoo since their 2024 updates. Without proper authentication, your messages are treated as suspicious by default and filtered into junk folders. Beyond authentication, you must maintain a healthy sender reputation by cleaning your list of invalid addresses, keeping spam complaint rates below 0.1%, and avoiding sudden spikes in sending volume.

Does buying an email list hurt deliverability?

Yes, buying an email list severely hurts deliverability because it introduces high bounce rates, spam traps, and unconsented contacts into your sending. These lists are a primary cause of high spam complaint rates and can get your domain blacklisted, causing long-term damage to your sender reputation. Open rates for purchased lists can be as low as 3%, compared to an industry average of over 19% for permission-based lists, signaling to mailbox providers that your emails are unwanted. Reputable email service providers prohibit using purchased lists, and doing so can result in account suspension or termination.

How long does it take to warm up a new email account?

Warming up a new email account takes a minimum of two to four weeks, with many experts recommending four to six weeks for cold outreach to achieve stable deliverability. The process involves starting with a low volume, such as 10-20 emails per day, and gradually increasing it to build a positive sending history with providers like Google and Microsoft. Rushing this schedule or sending a high volume from a new domain is a pattern that looks exactly like spam, which will cause your emails to be filtered. A successful warmup establishes your domain's reputation, and for best results, a low level of warmup activity should be maintained permanently alongside your campaigns.

Last updated: October 2026

How to Improve Email Deliverability: A Data-First Guide