Also known as: Inbox Placement, Inboxing
Email deliverability is the rate at which the emails you send actually reach subscribers' primary inbox rather than being blocked, bounced, or dumped into the spam folder. It is distinct from "delivery rate": an email can be delivered to the server yet still land in junk, where it earns nothing.
Inbox providers like Gmail, Outlook, and Yahoo decide placement using signals about who you are and how people react to you. Authentication (SPF, DKIM, DMARC) proves you are the real sender. Engagement (opens, replies, low complaints, few deletes-without-open) proves people want your mail. A clean sending domain and IP with a good reputation history proves you are not a spammer.
The economics are unforgiving for partners. If an IB has 20,000 subscribers but only 78% inbox placement, roughly 4,400 people never see the message. If each missed subscriber is worth even $0.50 in expected commission per campaign, a single send quietly loses about $2,200 in potential revenue to the spam folder.
Deliverability is not a one-time fix but an ongoing discipline. Sender reputation decays with every spam complaint, hard bounce, and spam-trap hit, and recovers slowly through consistent, engaged sends. Warming a new domain, pruning dead contacts, and honouring unsubscribes are the daily hygiene that keep an affiliate's funnel open.
Placement is a scoring process. When you send, the receiving provider evaluates authentication results, your domain and IP reputation, content signals, and how similar subscribers have engaged with you recently. A high score routes the mail to the inbox; a low score routes it to spam or blocks it outright.
Authentication is the entry ticket. SPF lists the servers allowed to send for your domain, DKIM cryptographically signs each message so it cannot be forged, and DMARC tells receivers what to do when SPF or DKIM fails. Without all three aligned, providers like Gmail now throttle or reject bulk senders.
Reputation is the ongoing verdict. Every open and reply nudges it up; every spam complaint, hard bounce, and spam-trap hit drags it down. Because reputation is tied to your sending domain and IP, protecting it means sending mainly to people who actually engage and removing those who do not.
Publish SPF, DKIM, and DMARC DNS records so inbox providers can verify you are the legitimate sender and not a spoofer.
Ramp send volume gradually over 2-4 weeks starting with your most engaged contacts, so providers build a positive reputation history.
Remove hard bounces, use a verification service on new sign-ups, and suppress contacts who have not opened in 90-180 days.
Balance value and promotion, avoid spam-trigger phrasing, and keep a healthy text-to-image ratio and a genuine unsubscribe link.
Track inbox placement, complaint rate, and bounce rate via tools like Google Postmaster; pause and diagnose when metrics slip.
Why it matters for partnership: If affiliate links land in spam, the IB's funnel collapses no matter how good the offer is. Strong deliverability keeps promotional emails in front of prospects, protecting the ROI of every lead the partner paid to acquire.
An affiliate emailing 30,000 subscribers through GetResponse sees opens fall as messages hit spam. After adding DKIM and DMARC and suppressing 6,000 contacts inactive for 120 days, Google Postmaster shows domain reputation move from "medium" to "high" and open rates climb from 14% to 22% within three weeks.
| Attribute | Delivery Rate | Inbox Placement |
|---|---|---|
| Measures | Accepted by the mail server | Landed in the primary inbox |
| Counts spam folder? | Yes, still counts as delivered | No, spam counts as a miss |
| Revenue impact | Misleadingly high | The number that actually matters |
Set up SPF, DKIM, and DMARC on your sending domain first, then monitor Google Postmaster Tools weekly to catch reputation drops before they crater your opens.
Using spam-trigger phrases like "make money fast" or "guaranteed profits" in subject lines, which trips filters and can bury an entire campaign in junk.
Aim for 90% or higher. Anything under about 85% means a meaningful share of your list never sees your emails and needs urgent list and authentication fixes.
Yes. Since 2024 Gmail and Yahoo require bulk senders to authenticate with all three, and unauthenticated bulk mail is throttled or rejected.
Common causes are a reputation hit from spam complaints, a spam-trap hit from a stale list, or a broken authentication record. Check Google Postmaster and your bounce logs first.
Confirm authentication is aligned, suppress everyone inactive for 90+ days, and send only to engaged contacts for a few weeks to rebuild reputation. There is no instant reset.
Severely. Purchased lists carry spam traps and unengaged addresses that trigger complaints and blocks, and they can get your domain blacklisted and your broker account banned.
Keep spam complaints under 0.1% (one in a thousand). Sustained rates above 0.3% will get you throttled or blocked by major providers.