How to fix a bad email sender reputation
What sender reputation is, how to tell that yours is damaged, and a four-week plan to repair it: stop the damage, clean the list, restart with engaged subscribers and rebuild volume.
Updated November 14, 2026 · 6 min read
Sender reputation is the trust mailbox providers place in your sending domain. Gmail, Yahoo and Outlook build it from how recipients treat your email: how many addresses bounce, how many people report spam, how many open and click. When it is damaged, your campaigns go to spam or arrive hours late, even for subscribers who want them. It can be repaired, and the repair is always the same: stop what is causing the damage, clean the list, restart with the people most likely to engage, and raise volume slowly.
How to tell your reputation is damaged
No single number is "your reputation". Each mailbox provider keeps its own. These are the signs to look for:
| Sign | Where to see it | Worry when |
|---|---|---|
| Spam complaint rate | Google Postmaster Tools | It approaches 0.3%; keep it under 0.1% |
| Hard bounce rate | Your campaign reports | Above 2% |
| Open rate at one provider | Your campaign reports, by recipient domain | It falls sharply at Gmail or Outlook while the others hold |
| Domain reputation | Google Postmaster Tools | "Low" or "Bad" |
| Bounce messages | Your campaign reports | They mention "blocked", "policy" or "reputation" |
A sudden drop in opens at one provider is the clearest signal. It means that provider has started sending your mail to spam.
What damages it
- Spam complaints. The strongest signal. Gmail and Yahoo both set the limit at 0.3% of delivered mail.
- Hard bounces. Mail to addresses that don't exist says the list wasn't collected from real signups.
- Spam traps. Addresses that exist only to catch senders using bought, scraped or very old lists.
- Volume spikes. A quiet domain that suddenly sends a large campaign looks compromised.
- Recipients who never engage. Months of unopened mail to the same people lowers placement for everyone on the list.
Nearly all of these come from one decision: emailing people who didn't ask to hear from you.
A four-week repair plan
Week 1: stop the damage
- Pause sends to your full list. Flows triggered by a customer's own action, such as an abandoned cart or an order, can keep running; they go to people who just engaged.
- Check authentication. SPF, DKIM and DMARC must all pass, and the From domain must match. See why your emails go to spam for how to check.
- Find the send that caused it. Look for the campaign where bounces or complaints jumped, and note which list or import it used.
Week 2: clean the list
- Remove every hard bounce and every complainer. They must never be emailed again.
- Remove the source of the problem. If one import or one signup form produced most of the bounces, take that whole group out.
- Set aside everyone who hasn't opened or bought in six months. Don't delete them; just stop including them.
- Close the door. Turn on double opt-in for the form that let bad addresses in.
Week 3: restart with engaged subscribers
Send to the people most likely to open: those who bought or signed up in the last 30 to 90 days. Send something worth opening, and keep the unsubscribe link obvious. High opens and near-zero complaints on these sends are what repair the reputation.
Week 4 onward: rebuild volume
Widen the audience in steps, adding the next most recent group each week and watching the complaint and bounce rates after every send. If either rises, go back one step. Keep a regular schedule; mailbox providers trust a steady sender more than an occasional one.
How Zalify handles this for you
Most of the plan above is built into how Zalify sends, and one page shows where you stand.
A sender reputation score. Email settings has a Sender reputation page with a score out of 100 and a level: Paused, Limited, Building, Good or Excellent. It shows what the score is made of:
- Recipients reached: how many different people you have emailed.
- Sending quality: hard bounces and complaints among the new recipients you emailed recently.
- Time sending: how long the domain has been sending, which is full after 30 days.
Below the score are any deductions, such as a daily allowance that was lowered after a bad day, and a list of steps that would raise it, each with the points it is worth.
Daily limits that follow your record. A new sender has a daily limit on first-time recipients, shown separately for campaigns, automated emails and transactional emails. The limit counts only people you have never emailed before; you can email people you have already reached as often as you need. It rises as your sends stay clean and is lowered after a day with too many bounces or complaints. This is the "raise volume slowly" step, enforced so that one large import can't undo your reputation in an afternoon.
Suppression you don't have to manage. Hard bounces, spam complaints and unsubscribes are suppressed automatically and skipped on every later send. Each broadcast's report shows who bounced, who complained and who was skipped.
A review before sending. A broadcast is checked before it goes out, first by an AI pre-review and then on our side, and automated emails in flows are reviewed the same way. Mail that would draw complaints is caught before it reaches a mailbox provider.
Permission by default. Marketing email goes only to contacts subscribed to it, every email carries one-click unsubscribe, and lists and forms can require double opt-in.
Read more about broadcasts and flows, or the deliverability practices in the help center.
What doesn't work
- A new domain. It has no history, and the same list will damage it the same way.
- A dedicated IP. It starts with no reputation and needs steady volume to warm up.
- Rewriting subject lines. Providers judge the sender and the recipients' reaction, not the wording.
- Sending more to make up for lower opens. More mail to people who aren't reading makes it worse.
Sources
- Email sender guidelines, Google Workspace Admin Help
- Sender best practices, Yahoo Sender Hub
- Outlook's new requirements for high-volume senders, Microsoft Tech Community
- Postmaster Tools, Google
Frequently asked questions
What is email sender reputation?
It is the trust mailbox providers such as Gmail, Yahoo and Outlook place in your sending domain and IP address. They build it from how recipients treat your mail: how many addresses bounce, how many people report spam, and how many open, reply or move the message to the inbox.
How do I check my sender reputation?
Register your domain in Google Postmaster Tools, which shows the spam rate and reputation Gmail assigns to it. Then look at your own numbers: a hard bounce rate above 2%, a complaint rate near 0.3% or open rates that fall suddenly at one mailbox provider all point to a damaged reputation.
How long does it take to repair a sender reputation?
Plan on two to four weeks of consistent, clean sending to engaged subscribers. A domain with a long good history that had one bad campaign recovers in days. A domain that sent to a bought list can take two months or more.
Should I switch to a new domain to escape a bad reputation?
Usually not. A new domain has no history, which providers treat with suspicion, and the same list and habits will damage it the same way. Fix the cause first. A new subdomain makes sense only after the list and sending practice are clean.
What damages sender reputation the most?
Spam complaints first, then hard bounces and hitting spam traps, all of which come from emailing people who didn't sign up. Sudden jumps in volume and long silences followed by a large send also count against you.
Does a dedicated IP address fix reputation?
No. A dedicated IP starts with no reputation and has to be warmed up with steady volume, which most stores don't send. Gmail in particular weighs the domain's reputation more than the IP's.
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