Email deliverability – the ability to get emails into subscribers’ inboxes rather than spam folders – is critical. In 2025, mailbox providers (Gmail, Outlook, Apple Mail, etc.) use sophisticated filters and engagement signals, making deliverability more complex but manageable with best practices. Follow the guidelines below to ensure your messages reach recipients’ primary inbox.•
Authenticate and Align Your Domain Set Up SPF, DKIM, and DMARC: These are must-have technical standards. SPF specifies which mail servers can send on your behalf; DKIM adds a cryptographic signature to prove legitimacy; DMARC ties it together with a policy telling providers what to do if checks fail . Without all three properly configured and aligned to your “From” domain, Gmail and others will likely flag your emails as suspicious .
In 2025, this is non-negotiable: always verify your DNS records for SPF/DKIM/ DMARC to match your sending domain. Salesforce and industry experts stress that “without authentication, Gmail, Yahoo, and Apple Mail will treat your emails as unauthenticated traffic, blocking or filtering them before they’re seen” . Use a Consistent, Branded “From” Address: Stick to one domain or subdomain (e.g. hello@yourbrand.com). Jumping between unrelated domains (promo@, info@, deals@) harms your sender reputation .
Every time the recipient sees your brand name and email address (e.g. yourcompany.com), their confidence grows. Mailbox providers also notice consistency; a stable domain history signals trust. As Tie (formerly Revenue Roll) advises, use a single, recognizable brand domain for the best long-term inbox placement . Warm Up New IPs and Domains: If you start sending from a new domain or IP, ramp up slowly. Begin with small sends (just to engaged subscribers) and gradually increase volume over weeks.
This tells providers that you’re a legitimate sender building a reputation. The Mailtrap guide specifically recommends gradually increasing sending volume for new IPs/domains . Many ESPs (Email Service Providers) offer “warm-up” features, or use tools like Lemwarm to automate this process. Always warm up before large campaigns to avoid sudden spikes that can trigger spam filtering. Maintain High List Quality Collect Permission (Opt-In): Only email people who explicitly opted in.
Double opt-in (requiring a confirmation click) can further ensure engaged subscribers. Never buy email lists or scrape contacts; this leads to low engagement and many bounces. Hygiene and Pruning: Regularly clean your list. Remove hard bounces (invalid addresses) immediately. Also prune unengaged subscribers (who haven’t opened or clicked in months). Continuously emailing unengaged addresses hurts your reputation. Aim for clean lists: an unsubscribe or inaction is preferable to a spam complaint.
As Mailtrap advises: “Maintain regular list hygiene remove invalid, unengaged, and bouncing addresses to protect your sender reputation and reduce spam trap hits” . This prevents hitting spam traps (which are often stealthy and pick up old or bought lists). Respect Unsubscribes: Make the unsubscribe process straightforward (one click). Each email must include a visible unsubscribe link. Providers view easy opt-outs as a sign you are a legitimate sender .
A rude pop-up or hidden unsubscribe can provoke complaints, which severely damage deliverability . Craft Non-Spammy Content Avoid Spam Trigger Words: Certain words or excessive punctuation (e.g. “FREE!!!”, “$$$”, “Act now!”) can flag spam filters. Keep subject lines and copy professional. According to OptinMonster , avoiding “spammy” language is crucial . •
Balance Text and Images: Emails that are one giant image often get flagged. Use a healthy mix of text and images. Also, always include alt text for images. Use Short, Engaging Subject Lines: Don’t oversell in the subject. Give a taste of the value (“Your free guide inside”) and avoid deceptive tactics. Avoid Large Attachments: These are often blocked or filtered. Host content online and link to it instead. Personalize and Relevance: As a best practice, tailor content to segments.
If recipients see content relevant to them, they will open and engage – and high engagement signals are key to deliverability . Mail servers track open and click rates; emails that get ignored repeatedly lose favor . So Test Before Sending: Use deliverability testing tools (like Mail-Tester , GlockApps) to score your email’s spamminess. Some ESPs even offer inbox testing (optimize subject lines, preview, etc.).
Monitor Sender Reputation Check Blacklists: Periodically check if your sending IP or domain is listed on email blocklists . If blacklisted, follow delisting procedures. Use ISP Feedback Tools: Gmail Postmaster and Microsoft SNDS let you monitor your IP’s reputation, spam complaint rates, and more. Mailtrap’s guide notes that analyzing authentication and reputation data from providers (like Google) is essential .
Watch Metrics: Track bounce rates (should be <2%), spam complaints (ideally <0.1%), and open/click rates. Sudden spikes in bounces or drops in engagement indicate issues. OptinMonster cites Constant Contact data showing a 10.29% average bounce rate ; aim to be well below that. Engagement is King Send to Engaged Users First: Prioritize sending your primary campaigns to subscribers who opened/clicked recent emails. Many ESPs allow this.
Engaged recipients tend to place mail in inboxes, which boosts overall deliverability. Reengagement Campaigns: Instead of continuing to email a completely cold list, send a re- engagement email (“We miss you – still want our tips?”). Those who don’t respond can be safely unsubscribed or moved to a very low-frequency segment. Mobile and Accessibility Optimize for Mobile: Over half of emails are read on phones. If your email appears broken on mobile, it reduces engagement (more deletes, less clicks).
Use responsive templates and concise copy. High mobile open rates are good; formatting issues are not. 50% of people delete an email if it’s not mobile-friendly . Poorly formatted content can drive unsubscribes or spam folder placements, so ensure mobile responsiveness and legible font sizes. One-Click Unsubscribe: Use mailto?unsubscribe links or built-in unsubscribe tags. Google even gives prominence to List-Unsubscribe headers.
Having a clear unsubscribe link or header is seen positively by email clients – ironically, making it easy to leave shows you respect the user and can boost deliverability . Embrace Evolving Standards BIMI (Brand Indicators for Message Identification): Consider implementing BIMI, which displays your brand logo alongside emails in Gmail/Outlook when authentication passes. It’s an emerging•
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standard that gives a trust signal to recipients, indirectly helping deliverability by improving brand recognition . Privacy Changes: Be aware of tracking-blocking features (like Apple’s Mail Privacy). Since actual open rates may drop due to image blocking, focus on click-through rates and domain reputation as success signals. Build engagement honestly rather than relying on open pixel data. Regulatory Compliance: Adhere to anti-spam laws (CAN-SPAM, GDPR, CASL).
Always use your legal business address in the footer , include “unsubscribe”, and only email those who consented. Providers filter out bulk senders who violate laws to protect users. By following these deliverability best practices, your emails will have a much better chance of landing in the inbox in 2025. In summary: authenticate your domain fully, maintain a clean and engaged list, craft legitimate, value-driven content, and monitor your sending reputation.
As industry experts note, getting it right can mean tens of percent more emails reaching the inbox . Ultimately, the more you align with ISP guidelines and subscriber expectations, the higher your inbox placement will be, yielding better