Glossary: deliverability
What is sender reputation in email?
Sender reputation is the level of trust that mailbox providers place in a sender, based on the past behavior of its domain and IP address. A good reputation sends email to the inbox. A poor one sends it to spam or blocks it.
What shapes sender reputation
Authentication
SPF, DKIM and DMARC in place
Bounces
Mail sent to dead addresses
Complaints
People marking mail as spam
Engagement
Opens, replies and deletes
Sender reputation is shaped by four signals.
Mailbox providers do not publish a score. They watch authentication, bounces, complaints and engagement, and they adjust where a sender's mail lands to match.
Authentication proves who is sending.
With SPF, DKIM and DMARC in place, mail can be shown to come from the domain it claims. Without them, reputation has nothing to attach to.
Bounces show list quality.
Mail sent to dead addresses tells providers the sender does not know its audience.
Complaints show unwanted mail.
People marking mail as spam count against the sender. It is a strong negative signal.
Engagement shows wanted mail.
Opens, replies and deletes are all read. Replies count in the sender's favor, and deletes without reading count against it.
Here is sender reputation at work for an invented company.
Imagine Ostermere, an invented freight software company. It sets up two sending domains and sends 1,000 emails from each. Domain A uses a verified list: it gets 8 bounces and 1 spam complaint. Domain B uses an old list nobody checked: it gets 90 bounces and 12 spam complaints.
The next week Ostermere sends the same email from both. From domain A, mail reaches the inbox. From domain B, mail starts landing in spam, because providers have learned from the 90 bounces and 12 complaints. Same company, same message, two reputations.
Two Ostermere domains after 1,000 emails each
Domain B: old list
- 90 bounces
- 12 spam complaints
- Mail starts landing in spam
Domain A: verified list
- 8 bounces
- 1 spam complaint
- Mail reaches the inbox
Protect sender reputation in four steps.
Reputation is slow to build and quick to lose, so the work is mostly prevention.
The four steps in order
- 1Authenticate
- 2Warm up
- 3Verify
- 4Watch signals
- 1
Authenticate every sending domain.
Publish SPF, DKIM and DMARC records before the first email.
- 2
Warm up new domains.
Raise sending volume gradually over several weeks so providers see a steady pattern.
- 3
Verify every list.
Remove invalid addresses before sending to keep bounces low.
- 4
Watch signals after every send.
Check bounces and complaints each time, and pause a mailbox whose numbers turn.
Prymatica sends from dedicated, warmed domains that are kept entirely separate from your primary domain, so your brand and main email reputation are never put at risk. See how Prymatica's cold email process works.
Teams make these mistakes with sender reputation.
Cold email goes out from the main domain.
If that domain's reputation drops, invoices and customer replies go to spam too. Use separate sending domains.
Volume jumps overnight.
A new domain that sends a thousand emails on day one looks like a spammer. Increase gradually.
Complaints are ignored.
A rising complaint count is an early sign of trouble. Change the list or the message before placement drops.
These glossary terms sit next to sender reputation.
These Prymatica pages go deeper on sender reputation.
Questions
People ask these questions about sender reputation.
How do you check sender reputation?
Some large mailbox providers offer dashboards that show how they rate your domain, and inbox placement tests show where your mail lands. Your own bounce and complaint counts are the day-to-day guide.
What damages sender reputation?
Many bounces, spam complaints, sudden jumps in volume, missing authentication and sending to addresses set up to catch spammers. All of them tell providers that the mail may be unwanted.
What is the difference between domain reputation and IP reputation?
Domain reputation follows the domain name in your sending address, wherever it sends from. IP reputation follows the server address the mail leaves from. Providers look at both.
How long does it take to repair sender reputation?
It takes weeks of clean sending: low volume, verified lists and mail people engage with. Building a good record is slower than losing one, which is why prevention matters.
Does a new domain start with a good sender reputation?
No. A new domain starts with no history at all, and providers treat unknown senders with caution. That is why a new sending domain is warmed up before it carries a campaign.
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