Back to Glossary
Deliverability

Sender Reputation

A score that email providers assign to your domain and IP based on your sending behavior and recipient engagement.

Definition

Sender reputation is a trust score that internet service providers (ISPs) and email providers assign to your sending domain and IP address. It is built over time based on factors like bounce rates, spam complaints, engagement metrics, authentication status, and sending patterns. A good reputation means better inbox placement; a poor reputation means more emails in spam. Think of it like a credit score for email sending.

Why It Matters

Your sender reputation is the single biggest factor in email deliverability. Even perfect content will land in spam if your reputation is poor. Building and maintaining a good reputation takes time and consistent good practices, while it can be damaged quickly by a single bad send. Email providers remember your history for months.

How It Works

Email providers track sending behavior from each domain and IP. They monitor how recipients interact with your emails: do they open them, click links, reply, or mark them as spam? They also track technical factors like bounce rates and authentication. This data forms your reputation score (typically 0-100), which influences filtering decisions for future emails. Gmail, Microsoft, and Yahoo each maintain their own reputation scores.

Example

A startup launches email marketing with a new domain:

  • Week 1: They send 50 emails to their most engaged users, getting 60% opens and 0 complaints
  • Week 2: They increase to 200 emails, maintaining high engagement
  • Week 4: They are sending 1,000 emails with 35% opens and minimal bounces
  • Week 8: They have built a strong reputation and can send 10,000+ emails with good inbox placement

Compare this to a company that bought a list and blasted 50,000 emails on day one - they got 15% bounces, 3% complaints, and are now blocked by Gmail.

Best Practices

  • 1Never send to purchased or scraped email lists
  • 2Make unsubscribing easy and honor requests within 24 hours
  • 3Remove bouncing addresses promptly from your list
  • 4Gradually warm up new domains and IPs before high-volume sending
  • 5Monitor feedback loops and address spam complaints immediately
  • 6Use Google Postmaster Tools to track your reputation with Gmail

Frequently Asked Questions

Use tools like Google Postmaster Tools (for Gmail), Microsoft SNDS (for Outlook/Hotmail), or third-party services like SenderScore.org. These show how major providers view your sending reputation on a scale of 0-100 or Low/Medium/High.

Building a solid reputation typically takes 4-8 weeks of consistent, good sending practices. Warming up a new IP or domain requires gradually increasing volume (double each week) while maintaining low bounce rates (<2%) and complaint rates (<0.1%).

Yes, but it takes time and effort. Stop bad practices immediately, clean your list thoroughly, reduce sending volume to only your most engaged subscribers, and rebuild slowly with consistently good practices over 6-12 weeks. Recovery is possible but slower than initial building.