Tired of your emails vanishing into the spam folder?
You wrote the email. The offer is solid. The copy is clean. You hit send and wait for replies, clicks, and sales. Then nothing happens. That silence usually isn’t a copy problem. It’s a deliverability problem.
A large share of legitimate marketing emails never make it to the inbox. Across 15 tested ESPs, the average deliverability rate for marketing emails is 83.1%, with 10.5% going to spam and 6.4% undelivered entirely. That’s the gap between “sent” and “seen.”
Most email deliverability checklist articles read like a glossary. SPF. DKIM. DMARC. Fine. But acronyms don’t fix inbox placement. Action does. This guide gives you the actual checklist. The same kind of practical, diagnostic sequence serious senders use to stop guessing and start fixing.
Before you touch a DNS record or rewrite a subject line, get a baseline. Run a free spam test on MailGenius. Send your message to the test address, see how mailbox providers are likely to treat it, and work from actual signals instead of assumptions.
If email is part of your revenue engine, treat it like infrastructure. That includes technical setup, list quality, and security hygiene. If your team also needs broader guidance outside deliverability, review these email security best practices for UK businesses.
1. SPF Sender Policy Framework Configuration
SPF is your first gate. If it’s wrong, you’re telling inbox providers that you either don’t know who’s allowed to send on behalf of your domain or you haven’t bothered to control it.
A simple example. Your team sends campaigns from Mailchimp, support emails from Google Workspace, invoices from Stripe, and outbound from a sales platform. If one of those senders isn’t included in SPF, that stream can fail authentication even when the email itself is legitimate.
What to check and why it matters
Check your domain’s SPF record in DNS and confirm every approved sender is included. Keep the record lean. If you pile in old vendors, duplicate includes, and random services nobody uses anymore, you create failures and confusion.
Mailbox providers use authentication as a trust signal. Post-2024 bulk sender requirements tightened expectations around proper setup and complaint control, which is why this isn’t optional for anyone sending at scale.
Practical rule: If a platform can send mail as your domain, it belongs in your SPF review. If it can’t send anymore, remove it.
How to test and pass fail rules
Run your domain through MailGenius before sending. If the test shows SPF missing, broken, or misaligned, fix it before the next campaign. You can use MailGenius to fix SPF, DKIM, and DMARC from one place instead of manually chasing scattered records.
Use this pass/fail standard:
- Pass: SPF exists, includes only approved senders, and aligns with your visible sending domain.
- Fail: No SPF record, outdated senders still listed, or a sending platform is missing.
Next steps are direct. Inventory every tool that sends mail. Update DNS. Retest. Don’t launch until SPF passes cleanly.
2. DKIM DomainKeys Identified Mail Implementation
DKIM proves your email wasn’t altered in transit and that it was signed by an authorized domain. If SPF says, “this server may send for me,” DKIM says, “this exact message is authentic.”
Gmail, Outlook, and other providers care about that signature because tampered mail looks like phishing. That matters even more if you use platforms like SendGrid or Mailgun, where the platform signs messages on your behalf and your domain has to be configured correctly.
What to check
Open a real email header from a recent send and look for a DKIM signature that passes. Don’t stop at “DKIM enabled” inside your ESP. Enabled in the dashboard and passing in the wild are not the same thing.
Use separate selectors when different platforms send different mail streams. Marketing, transactional, and outbound often behave differently. Keeping them distinct makes troubleshooting cleaner when one stream starts failing.
Why it matters and how to test it
A passing DKIM signature helps establish message integrity and domain trust. It also supports DMARC alignment, which becomes critical when you move from monitoring to enforcement.
Send a live test to MailGenius and verify the message is signed correctly. If the platform says DKIM is set up but MailGenius shows failure, trust the live result. That’s the one inbox providers see.
- Pass: The email arrives with a valid DKIM signature tied to your domain.
- Fail: No signature, bad selector, expired key, or alignment mismatch.
A common failure looks like this. A SaaS company rebrands, changes domains, keeps sending from the new domain, but leaves the old DKIM configuration in place on one automation platform. Marketing looks fine. Lifecycle emails start drifting into spam. The platform wasn’t broken. The setup was.
Retest after every platform change, domain change, or sending domain addition.
3. DMARC Domain based Message Authentication Policy Setup
Your team launches campaigns, receipts, and support emails from the same domain. One forgotten tool sends mail without alignment. The result is predictable. Some messages land in inboxes, some drift to spam, and spoofed mail still slips through under your brand. DMARC fixes that only if you set it up with intent.
DMARC tells inbox providers how to handle mail that claims to come from your domain but fails authentication. It also gives you reporting, which is how you find the platforms your team forgot about.
What to check
Check for a published DMARC record on the exact domain used in your From address. Then verify alignment on live messages, not just DNS. At least one of these must align with the visible From domain: SPF or DKIM.
Check the policy too. p=none is monitoring mode. p=quarantine starts pushing suspicious mail out of the inbox. p=reject tells providers to block it. If you jumped to enforcement before checking every sender, expect breakage.
Why it matters
DMARC is how you stop guessing which mail is legitimate. It cuts down spoofing, tightens authentication, and gives providers clearer instructions. That helps protect your domain and makes troubleshooting faster when placement drops.
It also forces operational discipline. If billing, support, CRM, outbound, and marketing tools all send as your domain, DMARC exposes the weak link fast.
Here’s the video version if you want to see the setup logic visually:
How to test with MailGenius
Send a real message from your production setup to MailGenius. Check whether DMARC exists, whether SPF or DKIM aligns with the From domain, and whether the policy matches your stage. If you also want to rule out reputation issues while you troubleshoot enforcement, run your domain through an email blacklist checker.
Trust the live result. That is what mailbox providers evaluate.
- Pass: A DMARC record is published, live mail shows aligned SPF or DKIM, and the policy matches your rollout stage.
- Fail: No DMARC record, no alignment, reporting addresses that do not work, or an enforcement policy published before all legitimate senders were validated.
A common failure is simple. Marketing passes. The help desk platform sends as the same domain but signs with its own domain and fails SPF alignment too. You publish p=reject, and support replies start disappearing. DMARC did its job. Your inventory of senders was incomplete.
Next steps
If you fail, do this in order. Inventory every platform that sends mail as your domain. Fix alignment on each one. Start with p=none while you review reports. Move to p=quarantine, then p=reject only after all legitimate streams pass.
Retest after every new tool, domain change, or sending workflow update. DMARC is not a one-time setup. It is a control layer that only works if your sender stack stays clean.
4. IP Reputation Monitoring and Management
Your campaigns look fine. The copy is clean, the domain is authenticated, and open rates still fall off a cliff. That usually points to reputation, not creative.
IP reputation affects how mailbox providers treat your mail before the message body gets much benefit of the doubt. If your sending pattern looks erratic, risky, or tied to past abuse, placement drops fast. That is why IP decisions matter. Use shared infrastructure if your volume is low and your provider manages it well. Move to a dedicated IP only when you send enough consistent volume to build and maintain your own reputation.
What to check and why it matters
Check four things first. Your sending setup, your recent volume pattern, your blacklist status, and any signs of throttling or temp failures from major providers.
A good IP can be damaged by bad behavior. Long gaps followed by sudden spikes are a common trigger. So is pushing cold lists, stale CRM exports, or recycled leads through a new IP. If you are warming up a dedicated IP, send to recent engagers first and raise volume in controlled steps. Reputation is built on consistency.
Shared versus dedicated is not a status symbol. It is an operating choice. If your volume is too low, a dedicated IP often makes things worse because you cannot produce the steady positive signal needed to keep it healthy.
How to test with MailGenius
Run your sending domain and IP through an email blacklist checker. Then match the result against your sending history from the last few weeks. If a listing showed up after a sharp volume increase, a bad import, or a new tool started sending, you likely found the cause.
Do not stop at the scan. Check your ESP logs for deferrals, rate limits, and provider-specific blocks. Reputation problems often show up there before the blacklist issue becomes obvious.
Pass or fail
- Pass: Sending volume is steady, the IP is not listed, and mailbox providers are not throttling or bulk-foldering your campaigns without a clear content issue.
- Fail: The IP is listed, delivery drops after volume spikes, major providers defer mail, or a new dedicated IP is being used without a warm-up plan.
Next steps
If you fail, stop broad sends first. Cut volume back to your highest-engagement segment and stabilize the pattern. Then review recent imports, suppress cold or risky segments, and identify any new platform that started sending through the same IP.
If you are on a dedicated IP and volume is inconsistent, reconsider the setup. A clean shared pool is often the smarter option until your volume is high enough to support a dedicated reputation.
Retest after every major sending change. New tools, new traffic sources, and sudden volume jumps can undo months of clean reputation work.
5. Email List Hygiene and Validation
You can have SPF, DKIM, DMARC, and a clean IP, then still miss the inbox because your list is bad. That happens all the time. Teams keep sending to old, unverified, low-intent contacts and blame deliverability tools when bounce rates and complaints climb.
What to check and why it matters
Start with source quality. Every contact on your list should have a clear origin and a reason to receive your email. If you cannot verify how an address was collected, suppress it. Purchased data, scraped contacts, stale event lists, and bloated CRM exports create the same pattern. More bounces, more complaints, worse inbox placement.
Then check recency and engagement. A contact who opted in two years ago and has ignored the last 20 campaigns is not an asset. That address is now a risk. List hygiene is not a cleanup task you do when metrics get ugly. It is ongoing reputation control.
How to test with MailGenius
Use MailGenius before a major send, but do it with a purpose. Test the actual campaign, then compare the result against the segment you plan to mail. If the message checks out technically and one segment still underperforms, your list quality is the likely problem.
Pair that test with your ESP data. Look at hard bounces, soft bounces, complaint spikes, unsubscribe spikes, and zero-engagement segments. MailGenius helps you rule out message-level issues so you can isolate list-level problems faster.
A practical pass/fail standard
Use a simple rule set.
- Pass: Contacts have a clear opt-in trail, recent engagement or customer activity, and no history of bouncing or complaining.
- Fail: The segment includes unknown-source contacts, old imports, typo-filled addresses, repeated non-openers, or anyone who has already hard bounced or complained.
Apply those rules at the record level.
- Keep: confirmed subscribers, active readers, recent buyers, and known customers
- Review: dormant leads, older webinar or lead magnet imports, and contacts with weak or outdated consent records
- Remove or suppress: hard bounces, complainers, role accounts when they do not belong, obvious typos, and addresses that repeatedly fail validation
A simple example. An ecommerce brand should send promos to recent buyers and active subscribers first. Older dormant contacts belong in a re-engagement segment with lower volume and a clear cutoff. If they do not respond, suppress them.
List size does not protect revenue. List quality protects inbox placement.
Next steps
If you fail this check, stop broad sends. Validate new entries at signup, suppress bad records before the next campaign, and cut unengaged segments out of your main flow. Then rebuild sending around verified, active contacts only.
From now on, treat hygiene as a standing rule. Clean at entry. Recheck before large campaigns. Suppress fast when a segment starts producing bounces or complaints. That discipline keeps one bad import from dragging down everything else you fixed.
6. Authentication Score Testing and Spam Filter Assessment
A lot of teams check DNS records, assume everything is fine, and then skip the only test that matters. Sending the actual email through a real spam assessment.
That’s where hidden problems show up. Broken HTML. Risky phrases. Link reputation. Missing plain text. Subject line formatting. AI-generated copy that reads fine to humans but still trips filters when combined with weak infrastructure.
What to check
Test the exact email you plan to send. Not a draft from last month. Not a stripped-down version with half the links removed. The actual message.
MailGenius is useful here because it checks more than raw authentication. It reviews content, links, domain signals, and structural issues in one pass. That gives you a diagnostic instead of a generic score with no context.
Why this step matters in 2026
Inbox providers don’t judge mail on one factor. They look at the sender, the message, the links, and the recipient response pattern. WordStream’s analysis points out a major blind spot in most guidance: teams often can’t tell whether low engagement comes from real inboxing problems or normal list fatigue, and the industry still lacks clear provider-specific engagement thresholds for that diagnosis as described in this gap analysis.
That’s exactly why pre-send testing matters. It helps you separate “the message is technically risky” from “the audience isn’t responding.”
- Pass: authentication is clean, links are safe, formatting is stable, and no major spam triggers appear.
- Fail: authentication breaks, spam flags appear, links look suspicious, or the HTML is sloppy.
If it fails, don’t rationalize it. Fix the issues and retest.
7. Reverse DNS PTR Record Configuration
Reverse DNS is one of those checks people ignore because it sounds too technical. Then they spend days chasing inbox issues caused by a mismatch that should’ve been fixed in minutes.
When a receiving server checks your sending IP, it often wants the reverse lookup to make sense. If the IP points to a hostname that doesn’t match your SMTP identity or looks generic and inconsistent, trust drops.
What to check
Check the PTR record on any dedicated sending IP. Then compare it to the hostname your mail server presents. If they don’t line up, fix that before you scale.
This matters most for teams running their own infrastructure, using dedicated IPs through providers, or splitting mail across multiple systems. SaaS apps with managed sending sometimes handle this for you. Sometimes they don’t.
How to test and what to do next
Use MailGenius to verify reverse DNS as part of your authentication review. If you identify a mismatch, use this guide to resolve email deliverability problems.
- Pass: your sending IP resolves cleanly to a hostname that matches your SMTP identity.
- Fail: no PTR record, generic mismatch, or inconsistent hostname presentation.
A common example is a company that moves transactional mail to a new dedicated IP but never updates PTR with the hosting provider. The campaigns aren’t the issue. The server identity is. Fix the DNS, retest, and then send.
8. BIMI Brand Indicators for Message Identification Implementation
BIMI won’t rescue a bad sender. But once your authentication is solid, BIMI helps reinforce legitimacy and brand recognition.
Think of it as the finishing layer on a disciplined setup. If your DMARC policy is weak or unenforced, you’re not ready. If your domain alignment is messy, you’re not ready. If those pieces are locked in, BIMI becomes worth doing.
What to check and why it matters
Check whether you already have enforced DMARC, a properly formatted BIMI record, and the brand assets required by the mailbox providers you care about. Then test whether the record resolves correctly.
For established brands, BIMI can support trust at the point of inbox decision. For smaller brands, it’s still useful, but only after the basics are fully in order.
Pass fail and next steps
Use a MailGenius test to validate whether BIMI is present and whether the email passes the prerequisites that make BIMI viable.
- Pass: enforced DMARC is in place and the BIMI record is correctly published.
- Fail: no enforcement, invalid record, or missing brand verification requirements.
A practical example. A retail brand with a clean domain, strong transactional mail, and consistent campaigns can justify BIMI because the brand recognition value compounds over time. A startup still fighting authentication failures should ignore BIMI for now and fix the core stack first.
9. Link Quality Shortened URLs and Broken Link Detection
A campaign can pass SPF, DKIM, and DMARC, then still miss the inbox because the links look shady.
That happens all the time with public shorteners, broken pages, bloated redirect chains, and tracking domains nobody recognizes. Mailbox providers do not judge links as an afterthought. They treat them as a trust signal.
What to check
Check every link in the email before send. Verify the final destination URL, every redirect in the path, the domain reputation of the landing page, and whether the visible call to action matches where the click goes.
Public shorteners like bit.ly and tinyurl are a bad choice for cold outreach and promotional mail. Use your own domain or a branded tracking domain you control. If a link points to a file, make sure the file loads cleanly and does not trigger browser warnings. If a landing page 404s, redirects to a generic homepage, or lands on a different domain than expected, fix it before launch.
Why it matters
Spam filters look for patterns tied to phishing and low-quality mail. Hidden destinations, mismatched anchor text, and redirect chains fit that pattern fast.
Recipients notice it too. A sketchy URL kills clicks. A broken page kills trust. Both problems train mailbox providers to treat your mail like something users do not want.
How to test it
Use MailGenius to inspect the message before you send it. Check whether your links resolve correctly, whether the tracking setup looks clean, and whether any destination raises trust issues.
Then click every link yourself on desktop and mobile. Do not delegate this. If the path feels confusing, slow, or inconsistent, clean it up.
Pass fail and next steps
- Pass: every link works, uses a trusted domain, resolves through a clean redirect path, and matches the promise in the copy.
- Fail: public shorteners, broken pages, mismatched destinations, unnecessary redirects, or low-trust domains appear anywhere in the email.
If it fails, remove the shortener first. Then replace weak destinations with pages hosted on your own domain or a branded subdomain you control. Cut redirect hops wherever possible. Re-test the message in MailGenius before it goes out.
If the URL looks questionable at a glance, the filter will question it too.
A practical example. An outbound team sends a sequence with a Calendly link, a Google Drive asset, and a bit.ly case study link. The bit.ly link is the first thing to kill. Host the case study on your own domain, keep the redirect path short, and make the CTA match the destination exactly.
10. Sender Name From Address and Email Headers Optimization
A prospect opens your email, sees “Marketing Team” from a vendor subdomain, and deletes it before reading the first line. That decision happens in seconds. Sender identity sets the tone before your copy gets a chance.
This is one of the easiest places to lose trust. A weak From name, a mismatched address, or sloppy header setup makes legitimate mail look disposable.
What to check
Review five items every time.
Your From name. Your From address. Your Reply-To. Your Return-Path alignment. Your unsubscribe header behavior.
Use names people recognize on sight. “Acme Billing” works. “Sarah at Acme” works for sales or account-based outreach. “Team,” “Notifications,” and “No Reply” waste trust and suppress replies.
Keep the identity matched to the message type. Billing mail should look like billing mail. Product alerts should come from product or support. Promotional campaigns should never hide behind a support-looking sender.
Why it matters
Mailbox providers evaluate technical setup, but recipients make the final call with opens, replies, deletions, and spam complaints. Confusing sender identity hurts those signals.
Header mismatches also create avoidable risk. If the visible From address says one thing and the underlying routing points somewhere else without clear alignment, filters have more reasons to scrutinize the message. Replies can break too, which costs you conversations you should have captured.
A clean sender identity does two jobs. It helps the recipient trust the email fast, and it helps your program stay consistent across campaigns.
How to test it
Send the message to MailGenius before launch and inspect the header details. Confirm the From name is clear, the From domain matches your brand, the Reply-To goes to a monitored inbox, and unsubscribe headers appear where they should.
Then view the message in a real inbox. Check the sender line on desktop and mobile. If the sender identity looks vague, truncated, or inconsistent with the email purpose, fix it before sending at scale.
Pass fail and next steps
- Pass: recognizable From name, brand-aligned From address, working Reply-To, clean header setup, and consistent sender identity across campaigns.
- Fail: generic names, misleading labels, third-party domain mismatch, broken reply handling, or missing unsubscribe header support.
If it fails, fix the From name first. Then move the From address onto a domain or subdomain you control, route replies to a real inbox, and standardize naming by email type. Re-test in MailGenius after every change.
A simple SaaS setup proves the point. Account alerts from “Acme Support” and invoices from “Acme Billing” are clear. Sending both from “[email protected]” tells the recipient nothing useful and makes the message harder to trust.
10-Point Email Deliverability Checklist Comparison
| Solution | 🔄 Implementation Complexity | ⚡ Resource Requirements | 📊 Expected Outcomes | 💡 Ideal Use Cases | ⭐ Key Advantages |
|---|---|---|---|---|---|
| SPF (Sender Policy Framework) Configuration | Low, DNS TXT update | Low, DNS access, list of senders | Improves sender verification and reduces spoofing; better inbox placement | All domains sending email; foundational auth | Widely supported, easy and free to implement |
| DKIM (DomainKeys Identified Mail) Implementation | Moderate, key gen + DNS + signing setup | Medium, key management, mail server/ESP config | Ensures message integrity; boosts sender reputation and delivery | Transactional and marketing emails; when content integrity matters | Cryptographic signatures that survive forwarding |
| DMARC (Policy Setup) | High, policy + reporting + cross-team coordination | High, SPF/DKIM in place, reporting tools, ongoing monitoring | Enforces authentication, prevents domain abuse, provides visibility via reports | Brand protection, phishing prevention, enterprise domains | Combines enforcement with visibility for domain protection |
| IP Reputation Monitoring & Management | Moderate, continuous tracking and remediation | Medium–High, monitoring tools, analyst time, delisting effort | Early detection of blacklisting; protects inbox rates and campaign ROI | High-volume senders; dedicated IP owners | Proactive identification and remediation of reputation issues |
| Email List Hygiene & Validation | Moderate, processes for validation and segmentation | Medium, validation services, time, integration effort | Lowers bounces and spam-trap hits; improves engagement and costs | Regular marketers, large subscriber bases, list imports | Dramatic reduction in bounces and improved sender reputation |
| Authentication Score Testing & Spam Filter Assessment | Low–Moderate, create tests and interpret results | Low–Medium, testing tools, multiple test runs | Identifies content/configuration blockers before production sends | Pre-send checks for major campaigns and new flows | Actionable, prioritized fixes to prevent campaign failures |
| Reverse DNS (PTR) Configuration | Low, request PTR via IP provider | Low, coordination with hosting/IP provider | Adds legitimacy signal; reduces spam scoring from receivers | New dedicated IPs or when PTR is missing/misconfigured | Simple, universally-checked verification step |
| BIMI (Brand Indicators for Message Identification) Implementation | High, requires DMARC enforcement and TMCH verification | High, trademark registration, SVG asset, DNS publishing | Increases brand visibility in inbox and may lift opens | Brands wanting visual inbox differentiation and trust signals | Distinguishes brand and signals strong authentication posture |
| Link Quality, Shortened URLs & Broken Link Detection | Moderate, regular audits and QA | Medium, link-scanning tools, QA processes, developer fixes | Reduces link-based spam triggers, improves UX and CTR | Marketing emails with many links, tracking/affiliate links | Prevents link reputation issues and broken-user experiences |
| Sender Name, From Address & Email Headers Optimization | Low–Moderate, policy, testing, ESP config | Low, coordination, header/header-field updates | Improves open rates and reduces spam filtering risk | All senders aiming to increase recognition and engagement | Quick wins for recipient trust and deliverability |
From Checklist to Inboxed Your Path Forward
Your team lines up a campaign, approves the copy, schedules the send, and expects results. Then opens sag, replies slow down, and nobody knows which part broke. That is what bad deliverability management looks like. You do not lose the inbox all at once. You lose it through small misses that stack up across authentication, reputation, list quality, links, and sender identity.
Use this checklist like an operating process. Check the 10 points before important sends, review them on a set schedule, and fix failures while they are still small. Weekly reviews are a smart standard. If you only look after performance drops, you are already late.
The point is simple. Stop treating deliverability like a postmortem.
Each item in this checklist should answer five questions. What should you check? Why does it matter? How do you test it, including a MailGenius check before send? Is it a pass or a fail? What happens next if it fails? That structure turns a generic best-practices list into a real action plan your team can use under pressure.
Start with the issues that can block mail immediately. SPF, DKIM, and DMARC. Then confirm the supporting signals, including PTR, sender identity, and link quality. After that, watch the systems that degrade over time, especially IP reputation and list hygiene. Finish with a live spam and authentication test on the actual message, because a technically correct setup can still fail once content, links, and headers are combined.
Professional senders do not guess. They test the email they are about to send.
If you want the fastest next step, run today’s message through a free spam test on MailGenius. You will see how the email is likely to be evaluated and which problems need attention first. That is more useful than changing random copy, blaming the subject line, or waiting for mailbox providers to filter you after the campaign goes out.
Deliverability improves when you remove obvious failure points one by one. Keep doing that, and inbox providers get fewer reasons to distrust your mail. The result is straightforward. More inbox placement, more opens, more clicks, more replies, and more revenue from the campaigns you are already sending.
Run your next campaign through MailGenius before you send it. The free spam test gives you a baseline score and shows you where your authentication, links, content, and infrastructure need work so you can fix problems before they cost you inbox placement.