What Is Sender Reputation and How Does It Affect Deliverability
Sender reputation is the score email providers assign to your email accounts and domains based on your sending behavior and recipient engagement. It is the single most influential factor in whether...
Sender reputation is the score email providers assign to your email accounts and domains based on your sending behavior and recipient engagement. It is the single most influential factor in whether your emails reach the inbox.
How sender reputation works
Think of sender reputation like a credit score. You start with a neutral standing. Positive actions — emails being opened, replied to, and moved to the inbox — build your score. Negative actions — spam complaints, bounces, low engagement, and blacklisting — damage your score. Email providers like Gmail and Microsoft use your sender reputation to make real-time decisions about where to place your emails. High reputation means primary inbox. Low reputation means spam folder. Medium reputation means your emails might land in different places for different recipients.
Domain reputation vs IP reputation
Your sender reputation has two components. Domain reputation is tied to your sending domain (e.g., yourcompany.com). IP reputation is tied to the IP address your emails are sent from. With Google Workspace and Microsoft 365, you share IPs with other senders on the platform, so domain reputation is the more controllable factor.
What builds reputation
High open rates, high reply rates, low bounce rates, low spam complaint rates, consistent sending volume, proper authentication, and warmup activity. All of these positive signals tell email providers that your emails are wanted and legitimate.
What damages reputation
High bounce rates (sending to invalid addresses), spam complaints (recipients marking you as spam), blacklisting, sudden volume spikes, sending from unauthenticated domains, and low engagement (your emails consistently being ignored or deleted without reading).
How to check your reputation
Google Postmaster Tools shows your domain reputation on a four-tier scale: High, Medium, Low, Bad. Check this weekly. Microsoft SNDS provides similar data for Outlook recipients. You can also test inbox placement as a proxy for reputation using the deliverability checker.
How to build reputation from scratch
New accounts start with no reputation. The fastest way to build positive reputation is through email warmup — a process where your account sends and receives emails that are opened, read, and replied to, simulating the behavior of a trusted sender. Warm Inboxes provides accounts that have already been through this process, so you start with established reputation instead of building from zero.
How to protect reputation
Once you have built a strong reputation, protect it by sending to verified lists, keeping volume consistent, monitoring engagement metrics, and responding quickly to any signs of decline. Reputation is easy to damage and slow to rebuild.
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