Updated: Jul 30, 2025

Gmail-specific best practices for email delivery

This guide provides useful deliverability insights and Gmail specific best practices to help improve inbox placement when sending to Gmail recipients.

Gmail over the last two decades

When Gmail launched on April 1, 2004, its promise of 1 GB of storage, advanced search capabilities, and built-in spam filtering was so bold that many thought it was an April Fool’s joke. But it wasn’t. In the years that followed, Gmail steadily redefined how email was delivered, organized, and filtered; introducing innovations like tabbed inboxes, threaded conversations, and adaptive spam detection. What started as a disruptive product is now one of the most technically advanced and influential platforms in email.

Today, Gmail claims to block more than 10 million spam emails per minute, with a spam detection accuracy of 99.9%. False positives, legitimate mail incorrectly routed to spam, are rare, with a misclassification rate below 0.05%. Their success stems from a layered, data-driven filtering architecture powered by advanced machine learning models and massive real-time feedback loops.

How Gmail’s filters affect your email

Gmail’s email filtering is far more advanced than most people realize. It’s not just about spammy words or sketchy links, it’s a constantly evolving layered system powered by machine learning, behavioral data, and billions of signals. Understanding how it works is key to improving deliverability.

Here’s a behind the scenes look at how Gmail makes inbox placement decisions:

TensorFlow: Their foundation

In 2017, Google publicly shared that Gmail had adopted TensorFlow, its open-source machine learning platform, as a core part of its spam detection initiatives. This shift enabled Gmail to process billions of emails per day using deep learning models trained on massive datasets of both spam and wanted mail.

But Gmail doesn’t rely on TensorFlow alone, its broader filtering stack includes infrastructure forensics, reputation scoring, and advanced models like LLMs that understand meaning and intent.

Smarter than just spam words

Gmail breaks down every email into components; words, phrases, structure, and converts them into machine-readable vectors. It uses:

Tokenization and embeddings to spot similarities between emails, even if they’re worded differently.
Large Language Models (LLMs) to evaluate tone, intent, and context, not just surface content.

This allows Gmail to flag messages that 'feel' like spam, even if they don’t contain classic red flags.

Pro Tip: Gmail’s filters don’t look for specific ‘bad words’, rather they analyze patterns at scale, which is why small formatting or wording changes can affect inbox placement. You might write a perfectly clean email, but if it resembles patterns from unwanted campaigns, it can still be filtered, especially if you’re sending at scale.

Real-time pattern detection

Gmail continuously groups messages into clusters based on structure, topic, and engagement history. This helps them:

Detect new spam or phishing waves before user reports.
Compare your content to emerging threats.
Flag campaigns that resemble known problematic mail from others.

Pro Tip: Even if your domain has never been blocked, your campaign can be deprioritized if it looks too much like a previously flagged template or structure from someone else.

Fingerprints, infrastructure, and link behavior

Not all filtering happens within deep learning models, some checks happen early in the delivery chain:

Gmail generates fingerprints of each message based on header patterns, content structure, and formatting traits.
It inspects technical headers for mismatches (e.g. From vs. Reply-To).
It evaluates links, all their redirects, and known tracker domains.

Pro Tip: For Gmail, quality matters more than quantity when it comes to links. A ‘quality’link typically points to a reputable, well established domain that matches your brand identity and has a clean history (i.e. not previously flagged for spam or abuse). Links that redirect through multiple hops, use URL shorteners, or point to low-trust or mismatched domains can raise red flags. And while a few links are fine, stuffing your message with too many links, especially promotional ones, can still degrade placement.

Inbox type classification (tabs)

Gmail doesn’t have just one inbox, it sorts messages into categories like Primary, Promotions, Social, and Updates using parallel classifiers. Despite what some may think, these are all inboxes. Gmail’s systems evaluate each message based on:

Layout and formatting (e.g., templates, buttons, language).
Sending behavior (e.g., frequency, volume, history).
Engagement patterns with similar campaigns.
Your recipient’s past interactions with your messages.

Newsletters that are well-structured, expected, and sent to engaged users often land in the Promotions tab, and that’s perfectly normal.

Pro Tip: As mentioned, the Promotions tab is the inbox. Gmail created it to help users organize marketing and newsletter content. Trying to ‘trick’ Gmail into the Primary tab by disguising your newsletter to look like a personal message (e.g., removing branding, using vague subject lines, or avoiding typical email formatting) isn’t just ineffective, it can actually hurt your deliverability. Gmail’s models are trained to detect these types of tactics and may penalize you for it.

Reputation and personalization

Gmail doesn’t use a single spam score. Instead, it builds multiple trust models:

Your domain/IP reputation.
Your content history and engagement trends.
Each recipient’s individual behavior with your mail.

That’s why the same campaign might land in Primary for one reader, Promotions for another, and Spam for someone who hasn’t opened in months.

Pro Tip: Gmail doesn’t treat all your recipients the same. It builds a unique filter for each recipient based on how they’ve interacted with your emails, and how others have too. That means the exact same message can show up in the Primary inbox for some readers, the Promotions tab for others, and the Spam folder for those who haven’t engaged in a while. Your sender reputation is shared, but inbox placement is personal.

Change takes time

One of the most common questions we hear is: Why are my open rates down?

In many cases, the answer is inbox placement. If your messages generally make it to the Primary folder but now Gmail starts placing your mail in the Promotions tab, or worse, in the Spam folder, your recipients may never see them, even if they opted in.

But fixing this generally doesn’t happen overnight. Gmail’s filtering systems are based on aggregate patterns and long term trends, not one-off actions. If you clean your list or improve your content today, Gmail often needs time to see that the signals have changed.

Here’s what to keep in mind:

Fixes often take 7-14 days to show results at Gmail, but are dependent on your mailing cadence.
Gmail avoids reacting too quickly to spikes (positive or negative).
Consistent improvement matters more than sudden changes or quick fixes.

Pro Tip: If your open rates at Gmail have dipped, don’t panic, but don’t expect instant recovery either. Gmail’s filters learn over time. Rebuilding trust, or healing a damaged reputation, takes steady, consistent sending to people who actually want your emails.

Bottom Line

Gmail’s filtering isn’t random, and it’s not just about having the right authentication. Their systems are incredibly good at spotting patterns, mapping behavior, and learning in real time. The smallest signals, like link structure, layout, or unsubscribe rates, can tip the scales one way or another.

Gmail-specific best practices

Not all deliverability best practices are created equal. These recommendations are specific to how Gmail evaluates mail based on its unique architecture, evolving standards, and inbox behavior models. While some guidance applies across all mailbox providers, this section focuses on what truly matters for Gmail.

Authenticate with SPF, DKIM, and DMARC — and align them

Gmail uses authentication to verify sender legitimacy, and as of 2024, requires bulk senders to implement SPF, DKIM, and DMARC. But simply having these records in place isn’t enough, Gmail also checks for alignment. That means your visible From address should match your authenticated domain (via the d= in DKIM and SPF authorization). Misaligned records or inconsistent authentication weakens trust and can quietly hurt inbox placement, even if the message is delivered / accepted.

Prune inactive Gmail recipients regularly

Gmail evaluates how recipients interact with your mail over time. Messages sent to disengaged Gmail users may stop reaching the inbox, even if they aren’t bouncing or unsubscribing.

Send only to Gmail addresses that have opened or clicked recently (generally within the last 3-6 months, shorter if you’re a daily sender). Continuing to mail inactive users teaches Gmail that your messages aren’t wanted, which can damage your reputation, even for your engaged readers.

Respect the Promotions tab

The Promotions tab is part of Gmail’s inbox, it was designed for marketing and newsletter content. Newsletters that are expected, well-structured, and sent to engaged recipients often land there by design.

Trying to manipulate placement into the Primary tab, by stripping branding, mimicking personal messaging, or sending plain-text mail that pretends to be one-to-one can backfire. Gmail detects these tactics and may penalize them, pushing messages further toward Spam.

Avoid link shorteners and untrusted redirects

Gmail inspects every link in your message, including redirects and tracking domains. It evaluates the final destination for reputation, relevance, and trustworthiness.

Avoid using public link shorteners like bit.ly, tinyurl, or redirect chains through low trust domains. Even a single link pointing to a mismatched or questionable domain, anywhere in the hop, can result in filtering regardless of how clean the rest of your message is.

Monitor your reputation in Google Postmaster Tools

Postmaster Tools is Gmail’s official window into how it views your sending behavior. It provides domain and IP level insights into reputation, spam complaint rates, authentication health, and more.

While the data is high-level and not real-time, it’s an important tool for identifying early warning signs. A drop from ‘High’ to ‘Low’ or ‘Bad’ in domain reputation usually means Gmail is already changing how it treats your mail, whether you’ve noticed in your open rates yet. Go here to learn more about Google Postmaster Tools.

Maintain a consistent sending identity

Gmail builds a behavioral profile around your sending domain, From address, Reply-To, and sending infrastructure. Swapping domains, using inconsistent subdomains, or constantly changing sender names can interrupt this trust building process.

Stick to one identity per publication or brand. The more consistent your sending setup, the easier it is for Gmail to assign reputation accurately, and the better your chances of inbox placement.

Avoid sudden volume spikes or irregular sends

Gmail monitors send patterns. A sudden surge in volume, or a long period of silence followed by a large send can trigger rate limiting, deferrals, or placement into Promotions or Spam. If you’re ramping up volume or reactivating a dormant list, do so gradually. Gmail rewards consistency and predictability.

Use clear, honest subject lines

Gmail’s filtering systems, especially its LLM based models, evaluate subject line tone and intent. Vague or misleading subjects like ‘Quick question’ or ‘Just checking in’ used for newsletters or offers may be flagged as deceptive.

Use subject lines that reflect the actual content of the email. Transparency and clarity aren’t just good for engagement, they’re also part of building long term trust.

Don’t assume delivery means visibility

Gmail will silently suppress delivery to ‘dead’ or abandoned accounts where mail is accepted but never seen. This invisible suppression contributes to low open rates and reputational decline. Pruning these addresses is critical, even without bounce signals.

Understand that Gmail sometimes A/B tests placement

Gmail occasionally tests the same message in multiple inbox tabs (or filters it for some but not others) to see how users engage. This explains why a perfectly legitimate message may appear in Primary for one user, Promotions for another, and Spam for a third. These experiments are normal and based on user level behavior. Focus on performance trends over time, not single send outcomes.

Understand Gmail’s rate limits; Gmail will defer or temp fail mail if you send too much too fast. If you have a large list, think about breaking it up and sending multiple campaigns rather than one big blast.

A single large send gives Gmail one big data point to evaluate reputation. With smaller sends, it gives them more data points to look at. With one send, if even a small percentage of recipients bounce, complain, or don’t engage, the negative signals are concentrated. With segmented sends, each batch can stand on its own. If one send performs poorly, it doesn't drag down the reputation for the others as harshly.

Pro Tip: Avoid sending mail at the top or bottom of the hour. Far less traffic is sent to Gmail at off-times (e.g. 7:23, 7:42, etc.) which decreases the likelihood of rate limiting or deferrals.

How beehiiv supports you

Delivering email to Gmail can be both an art and a science, one that evolves constantly. What works for you today might not work tomorrow. At beehiiv, we’re deeply invested in helping our customers succeed by maintaining high deliverability standards, monitoring emerging trends, and proactively supporting healthy sending behavior. Our Deliverability team is here to ensure you’re not just sending email, by building a lasting sender reputation that earns trust, engagement, and inbox placement over time.