Sender reputation
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A score assigned to your email domain and IP address by email providers. Determines whether your emails reach the inbox or spam folder.
Sender reputation is a score that email providers (Gmail, Microsoft, Yahoo) assign to your sending domain and IP address. High reputation means strong email deliverability: emails go to the inbox. Low reputation: emails go to spam.
Reputation is built over time through consistent, legitimate sending. It is damaged by high bounce rates, spam complaints, spam trap hits, and sending volume spikes. Rebuilding a damaged reputation takes weeks to months of careful sending.
Think of sender reputation like a credit score. It takes years to build and moments to destroy. One bad campaign (sending to a purchased list, blasting 50,000 emails without warming up) can tank your reputation and affect every email you send for months.
Examples
A new domain builds reputation.
The company launches a new product with a new domain. Day 1: send 50 emails to the most engaged contacts. Day 7: send 200. Day 14: send 500. Day 30: send 2,000. Gradual volume increase builds reputation safely. Starting with 10,000 emails on day 1 would get flagged as spam.
Reputation damage from a cold outreach campaign.
The sales team sends 8,000 cold emails in one day. Spam complaint rate: 1.5%. Google marks the domain as a spammer. Marketing newsletter deliverability drops from 97% to 72%. The domain takes 6 weeks to recover with a careful warm-up process.
Monitoring sender reputation.
The marketing team checks Google Postmaster Tools weekly. Reputation is rated High. One week it drops to Medium after a large campaign with high bounce rate. They pause sending, clean the list, and reputation recovers to High in two weeks.
In practice
Read more on the blog
Frequently asked questions
How do you check your sender reputation?
Use Google Postmaster Tools for Gmail delivery data, Microsoft SNDS for Outlook, and third-party tools like Sender Score (by Validity) for an aggregate score. Check weekly and investigate any drops immediately.
How do you rebuild a damaged sender reputation?
Reduce sending volume dramatically. Send only to your most engaged contacts (opened in last 30 days). Gradually increase volume over 4-6 weeks. Remove all bouncing addresses. Monitor spam complaint rates and keep them below 0.1%. It is a slow process.
Related terms
The percentage of sent emails that actually reach the recipient's inbox. The foundation of every email marketing program.
The percentage of sent emails that were not delivered. Hard bounces are permanent failures. Soft bounces are temporary.
The percentage of delivered emails that recipients opened. A proxy for subject line effectiveness and sender trust.
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