Email deliverability is the discipline of getting the email you send to actually land in the inbox – not the spam folder, not a promotions tab nobody opens, and not a silent block at the gateway. It is the single biggest factor that separates email programs that work from ones that quietly fail, and it has almost nothing to do with how good your email looks. This hub is ToolTrusted’s home for deliverability: how it works, what breaks it, and exactly what to do about it. Everything here is vendor-neutral and grounded in hands-on testing rather than vendor marketing. Run a free email deliverability test to see exactly where your domain stands, then use the playbook below to fix what it finds.
Want a transparent, accessible alternative to an enterprise reputation suite? See ToolTrusted vs Validity. Managing deliverability across an in-house team? See ToolTrusted for teams.
What deliverability actually depends on
Mailbox providers like Gmail, Outlook and Yahoo decide where your mail goes using a handful of signals, in roughly this order of impact: who you are (authentication and reputation), whether recipients want your mail (engagement), and what you sent (content and links). Most “spam folder” problems are reputation and authentication problems wearing a content costume. The pillars below are the levers that move the needle.
- Sender reputation – the trust score mailbox providers assign to your sending domain and IP, built from complaint rates, spam-trap hits, and how recipients engage.
- Domain & IP warm-up – gradually ramping volume on a new domain or IP so providers learn you are a legitimate sender before you send at scale.
- Spam filters – how content, links, authentication and reputation are scored together, and why “spammy words” are the least important part.
- Blacklists (DNSBLs) – what gets you listed on Spamhaus and others, how to check, and how to request delisting.
- Bounce & complaint management – promptly suppressing hard bounces and complaints to protect reputation.
- Throttling & sending patterns – pacing volume and keeping a consistent cadence so you do not trip rate limits.
Authentication is the foundation
You cannot fix email deliverability without first proving your mail is really yours. As of 2024, Google, Yahoo and Microsoft require bulk senders to authenticate with SPF, DKIM and DMARC (RFC 7489) – without them, your mail is increasingly rejected outright. Start with our email authentication hub to get SPF, DKIM and DMARC configured correctly, then come back here for reputation and inbox-placement work. The two topics are inseparable: authentication is the lock, reputation is the key.
How well is the rest of the web actually doing this? In our original study of 10,000 top domains, 76.6% publish a DMARC record but only 54% enforce it – a reminder that publishing and protecting are not the same thing. See the full 2026 email authentication statistics.
How we test deliverability
When we evaluate a sending platform or SMTP service, email deliverability is not a checkbox – it is measured. We send real campaigns to seed lists across the major mailbox providers, record inbox-versus-spam placement, and check how each provider handles authentication, bounce suppression and reputation policy. You can read the full method on our how we test page, and see it applied across our tool reviews and SMTP service comparisons.
Start here
- Email Deliverability Guide 2026 – SPF, DKIM, DMARC and a 30-day warm-up plan.
- Email Authentication hub – get SPF, DKIM and DMARC right first.
- Reverse DNS (PTR) – the sending-IP requirement Gmail and Yahoo enforce on every sender.
- MX records – how inbound mail is routed to your servers.
- SMTP Services – the relays and APIs that send your mail, ranked on deliverability.
- Browse all deliverability articles.
How to improve email deliverability
To improve email deliverability, work the full lifecycle in order – meet the provider rules, warm up a new sender, grow and protect its reputation, get into the inbox, manage bounces and complaints, stay off blacklists, and measure it all with the right tools. These guides cover each step:
- Sender requirements – the Gmail, Yahoo and Microsoft bulk-sender rules you must meet to deliver at all.
- Email warm-up – ramp a new IP or domain safely with an engagement-first schedule.
- Sender reputation – the IP and domain signals that decide your fate, and how to monitor and improve them.
- Inbox placement & spam filters – why mail goes to spam and how to measure and fix placement.
- Bounce & complaint management – hard vs soft bounces, suppression, feedback loops and throttling.
- Email blacklists – which lists matter, how to check, and how to get removed.
- Best email deliverability tools – the inbox-placement testers and reputation monitors to measure it all, including the best free options.
More email deliverability guides are added to the deliverability category as they go live.
New to your result? Our guide to reading your Email Health Score breaks down the bands, the points ledger and exactly what to fix first. Managing deliverability for many client domains? See how agencies monitor every client’s email in one portfolio and get alerted before a client notices.
Continue across the platform
ToolTrusted covers the whole email stack. Wherever you go next, it connects back here:
- The ToolTrusted Platform – continuous monitoring, incidents, analytics, recommendations, benchmarking and automation.
- How It Works – the whole Email Health journey – check, report, save, track and monitor.
- Email Health Check – score your domain out of 100 across authentication, infrastructure, security and reputation.
- Research & Benchmarks – original data on SPF, DKIM and DMARC across 10,000 domains.
- Compare ToolTrusted – honest, side-by-side comparisons with MXToolbox, DMARCian, EasyDMARC and more.
- For Agencies – watch every client domain from one independent, white-label portfolio.
- Email Authentication – SPF, DKIM, DMARC, BIMI and the full DNS stack.
- SMTP Services – SES, Mailgun, Postmark and more, ranked on deliverability.
- Email Verification – list cleaning and inbox-placement testing tools.
- Email Security – stop spoofing and phishing, and encrypt delivery.
- Email APIs – transactional and marketing APIs for developers.
- Email Marketing – hands-on platform reviews, comparisons and best-of roundups.
Frequently asked questions
Why do my emails go to spam even though they look fine?
Almost always because of authentication or reputation, not content. If SPF, DKIM and DMARC are missing or misaligned, or if your domain or IP has low reputation from past complaints or a cold start, mailbox providers route you to spam regardless of how clean the email looks. Fix authentication first, then work on engagement and warm-up.
What is a good email deliverability rate?
“Delivery rate” (accepted by the server) is often 98%+ and tells you little. The number that matters is your inbox placement rate – the share of accepted mail that lands in the inbox rather than spam. Strong senders sustain an inbox placement rate in the high 80s to 90s percent; consistently below ~80% signals a reputation or authentication problem worth investigating.
Do I need a dedicated IP for good deliverability?
Not usually. A dedicated IP only helps if you send enough consistent volume (roughly tens of thousands of emails per week) to maintain its own reputation; below that, a well-managed shared IP pool from a reputable provider almost always delivers better. Reputation lives mostly at the domain level now, so authentication and list hygiene matter more than IP type for most senders.
How do I test my email deliverability?
Run a free email deliverability test – our Email Health Check scores your domain across authentication, infrastructure, security and reputation, so you can see what is hurting placement before you send. For true inbox-versus-spam results, pair it with seed-list inbox-placement testing across the major mailbox providers.