Setup Guide
How Gmail decides whether
to trust your emails
This page explains how reputation works — what the signals are, how they’re measured, and what damages them. For a quick practical checklist of what to check right now, see the Domain Health Checklist.
Every domain that sends email has a reputation score. Gmail, Outlook, and Yahoo each maintain their own version. When your score is high, your emails reach the inbox. When it drops, they go to spam — even if your content is perfect and your list is clean.
The #1 thing that damages sender reputation? Bounces from addresses that don’t exist. In other words: sending to an unverified list.
What you’ll learn
- What sender reputation is and who assigns it
- The five signals that raise or lower your score
- How unverified lists directly damage your reputation
- How to check your reputation and what to do when it drops
What sender reputation is
Every time you send an email, the recipient’s email provider (Gmail, Outlook, Yahoo) checks your domain against a trust score they’ve been building over time. This score is called your sender reputation.
It’s not a single number you can look up in one place. Each provider calculates it differently, using their own data. But the inputs are similar across all of them:
| Signal | What it measures | How verification helps |
|---|---|---|
| Bounce rate | Percentage of your emails that bounce back as undeliverable | Removes invalid addresses before you send. Keeps bounces under 1%. |
| Spam complaints | How often recipients mark your email as spam | Removes role-based and stale addresses that are more likely to complain. |
| Spam trap hits | Whether you’re sending to addresses designed to catch bad senders | Prevents hitting spam traps by sending to opt-in addresses and re-verifying lists every 60–90 days to remove invalid emails. Full guide → |
| Engagement | Opens, clicks, replies — do people actually interact with your emails? | Indirect: removing dead addresses means your engagement rate is measured against real people only. |
| Sending consistency | Steady, predictable sending vs sudden spikes | Indirect: clean lists reduce the need for sudden large sends after recovering from bounces. |
Three of the five signals are directly controlled by list quality: Bounce rate, spam complaints, and spam trap hits. Bounce rate and spam complaints are caused by sending to addresses that shouldn’t be on your email list. Verification eliminates both before you send. The third signal, spam traps, is separate: reverifying email lists every 60-90 days removes invalid emails that can potentially be turned into spam traps in future in order to detect unwanted sending.
Good reputation vs damaged reputation
Healthy reputation
<1%
Bounce rate. Emails reach inboxes. Gmail trusts your domain. Opens and clicks are measured against real people.
Damaged reputation
>2%
Bounce rate. Gmail starts routing emails to spam. Even verified addresses get affected — the damage hits your entire domain.
Healthy reputation
<0.1%
Spam complaint rate. Google requires bulk senders to stay under 0.3%. Best senders stay under 0.1%.
Damaged reputation
>0.3%
Spam complaint rate. Google flags your domain. Recovery takes weeks of clean sends with low volume.
The critical threshold: Google requires all bulk senders (5,000+ emails per day) to keep spam complaints under 0.3% and bounce rates low. Yahoo and Microsoft have similar standards. Cross these thresholds and your emails go to spam — often without warning.
How to check your reputation
Google Postmaster Tools (free) is the most direct way to see how Gmail views your domain. It shows your domain reputation (High, Medium, Low, Bad), spam rate, and authentication status. If you send any volume of email, set this up.
Microsoft SNDS (Smart Network Data Services) shows how Outlook views your sending IP. Less granular than Google but useful if you send heavily to Outlook/Hotmail.
QEV’s IP Blacklist Checker tells you if your IP is on major blocklists — a signal that your reputation has already been severely damaged.
When your reputation drops: what to do
1
Stop sending. Don’t send more emails into the problem.
2
Re-verify your entire list with QEV. Remove everything that isn’t safe to send.
3
Check authentication (SPF, DKIM, DMARC) and blacklists.
4
Resume sending at low volume — through your ESP (ActiveCampaign, Mailchimp) or sequencer (Instantly, Lemlist) — with clean list only. Rebuild over 2-4 weeks. Warmup guide →
Recovery takes time. There’s no shortcut. The only way to rebuild reputation is consistent, clean sending over weeks. Which means step 2 — re-verifying your list — is non-negotiable. You can’t rebuild reputation while still sending to bad addresses.
Sender Reputation — Quick Reference
What it is
A trust score Gmail, Outlook, and Yahoo assign to your domain based on your sending behavior
Top 3 killers
Bounces (>2%) and spam complaints (>0.3%), both caused by unverified lists, and spam trap hits caused by sending to purchased addresses and stale lists
How to check
Prevention
Verify before every send. Re-verify every 60-90 days. Keep bounces under 1%.
Recovery
Stop → re-verify → check authentication → rebuild at low volume over 2-4 weeks
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