Videos, written guides, and a jargon-free glossary covering everything we’ve learned about reaching the inbox: authentication, sender reputation, placement testing, and the mistakes that send mail to spam.
Teaches the fast pre-send routine and how to use the Unspam spam checker, so you can spot inbox risks before you hit send.
5:04
Walk through a complete deliverability check in five minutes using two free tools: spam score, inbox placement, and the fixes that move the needle fastest.
2:45
A walkthrough of the Unspam spam checker and deliverability test: what each score signal means and how to act on it before you hit send.
Teaches how a full deliverability audit differs from a one-off spam test, so you know which diagnostic to reach for and how to read what it finds.
5:21
Why revenue keeps dropping even when your emails “send”: the difference between a spam test and a deliverability audit, and when each one is the right call.
5:05
The signals reshaping inbox placement going into 2026: engagement weighting, authentication enforcement, and what the year’s data tells us about where mail actually lands.
Two long-form webinars that connect the fundamentals to the current state of the inbox and proven tactics for high-stakes sending seasons.
1:06:03
A full webinar with Email Industries on the real state of email deliverability: what’s working in 2025, what’s broken, and the diagnostic playbook senders should run.
1:06:04
A full webinar on holiday-season deliverability: authentication, branded links, volume strategy, list hygiene, engagement signals, and the privacy laws that affect your sends.
The concepts behind every test. Read these once and the rest of the Academy makes more sense.
There is no single rulebook. Gmail, Yahoo, Outlook, and Apple Mail each run their own filtering, and they weigh dozens of signals on every message: who is sending, whether the message is authenticated, how recipients have treated your past mail, and what the content looks like. The decision is per message and per recipient, not a fixed verdict on your domain.
Think of it as a running score rather than a gate. Strong authentication and a clean reputation earn you the benefit of the doubt; a spike in complaints or a cold, unengaged list erodes it fast. The same email can reach one subscriber's inbox and another's spam folder because their individual history with you differs.
Because the logic is hidden and changes often, you cannot reverse-engineer a guaranteed inbox. What you can do is control the inputs the filters reward, then measure placement directly with an inbox placement test instead of guessing from open rates.
Authentication proves a message genuinely came from you and was not forged in transit. SPF lists which servers are allowed to send for your domain. DKIM signs each message with a private key so the receiver can verify it against a public key published in your DNS. DMARC ties these together: it passes when SPF or DKIM passes and the result aligns with the visible From domain, and it tells receivers what to do when checks fail.
Your DMARC policy escalates through three levels: p=none watches without acting, p=quarantine sends failures to spam, and p=reject blocks them outright. Since the Google and Yahoo bulk-sender rules took effect in February 2024, any sender of roughly 5,000 or more messages a day to Gmail must have SPF, DKIM, and at least a p=none DMARC policy in place. One detail trips people up: SPF evaluation is capped at 10 DNS lookups, and exceeding it returns a permerror that quietly breaks the record.
BIMI is the optional layer on top. With DMARC at enforcement (p=quarantine or p=reject), BIMI can display your verified logo next to the message in supporting clients. You can confirm all four records resolve correctly with the free SPF, DKIM, DMARC, and BIMI checkers.
Reputation is the trust score mailbox providers attach to the sources you send from. It splits across two layers: your sending domain, which travels with you wherever you send, and the IP address that actually transmits the mail. Domain reputation is the more durable of the two, which is why protecting it matters more than chasing a clean IP.
Reputation is earned over time and through consistency. Providers watch your volume patterns, complaint rates, bounce rates, and how recipients engage. A sudden jump in volume from a cold domain reads as suspicious, which is why new domains and IPs need a gradual ramp before they carry full volume. Shared IPs mean you also inherit the behavior of every other sender on that address.
Damage is asymmetric: reputation drops quickly after a bad send and recovers slowly through sustained good behavior. The practical takeaway is to keep volume steady, fix complaint sources fast, and avoid sending to addresses you have not built a relationship with.
Mailbox providers want to deliver mail people actually want, so they lean hard on how recipients behave. Opens, replies, forwards, and moving a message out of spam are positive signals. Deleting without reading, ignoring mail for weeks, or hitting the spam button are negative ones. Over time these signals shape where your future mail lands for each recipient.
This is why authentication and a clean list get you to the door but engagement decides whether you stay in the inbox. A domain with perfect SPF, DKIM, and DMARC will still slide toward spam if subscribers consistently ignore it. Conversely, a segment that opens and clicks reliably builds inbox placement that protects your whole program.
The actionable response is to send to people who want your mail and to suppress the ones who do not. Segment by recent activity, slow down or stop mailing dormant contacts, and treat a falling engagement rate as an early warning long before it shows up as a deliverability problem.
A clean list is one of the strongest deliverability levers you control. Hard bounces are permanent failures from invalid addresses, and continuing to mail them tells providers you are not maintaining your list. Complaints happen when recipients mark you as spam; the Google and Yahoo rules require keeping that rate below 0.3% and ideally under 0.1%, because a high complaint rate is one of the fastest ways to land in spam.
Spam traps are the most dangerous entries. These are addresses that should never receive mail: recycled traps were once real but abandoned, and pristine traps were created solely to catch senders who harvested or bought lists. Hitting them signals poor list acquisition and can trigger blacklisting.
Hygiene is ongoing, not one-time. Remove hard bounces immediately, honor unsubscribes promptly with one-click List-Unsubscribe, and suppress long-dormant contacts before they decay into traps. Validating addresses before you send is the cleanest prevention, which is what email verification is for.
Content is both a filtering signal and a rendering risk. Filters read your subject, body, links, and image-to-text balance, and patterns common to spam, such as misleading subjects, link shorteners, or broken authentication on tracking domains, can pull your score down. Branded, consistent sending domains for your links help more than borrowed or unfamiliar ones.
Rendering is the other half. An email that scores clean can still fail if it breaks across clients. Gmail, Outlook, Apple Mail, and mobile apps each interpret HTML differently, so a layout that looks right in one can collapse in another, and dark mode, image blocking, and clipped messages all change what recipients actually see.
A pre-send test catches both before your list does. Running a spam-score test surfaces content and authentication problems while previews show how the message renders across real clients, so you fix issues once instead of learning about them from a drop in results.
Run this before any campaign. Most steps take minutes with a free tool.
Every acronym a sender runs into, defined without the jargon.
Free spam check, deliverability score, and an AI action plan, all in under 30 seconds.
