The deliverability of email is determined by individual recipient relationships with your sending domain—not abstract "domain reputation" scores. What people call "ESP reputation" is actually a derivative measure: an aggregate of millions of individual recipient relationships. The unit of reputation isn't domain→server, it's domain→recipient.

The Relationship Model
YOUR
DOMAIN
Sending Domain
jane@gmail.com Opens, clicks, never marks spam
mike@outlook.com Ignores most, occasional open
sara@yahoo.com Marked as spam twice

Each recipient has their own relationship with your domain. Gmail aggregates all Gmail recipient relationships. That aggregate is your "Gmail reputation."

Two Models of Reputation
Conventional Wisdom

Domain Reputation

Your domain has a "score" that exists as a property of the domain itself. Focus on authentication, warm-up, and "list cleaning."

If reputation drops, change ESPs or start a new domain. The score is what matters.

Monitor domain reputation scores. Clean your list periodically.

The Reality

Recipient Relationships

Each recipient has their own relationship with your domain based on their behavior: opens, clicks, ignores, spam complaints. Gmail aggregates all Gmail users' relationships with you.

"Domain reputation" is just the aggregate. The unit that matters is the individual recipient.

Monitor individual engagement. Every recipient relationship matters.

Observable Evidence
01

Email migrates between domains, reputation doesn't.

When you switch from old-domain.com to new-domain.com, mail from the new domain starts fresh—inbox placement is terrible initially. It improves as you build new relationships. Reputation is relational, not portable.

02

Same ESP, different domains, different results.

Two companies using the same ESP sending similar volume see wildly different inbox placement. Their domains have different histories, different relationships with Gmail/Outlook/Yahoo.

03

High-volume senders get preferential treatment.

Yahoo, Gmail, Outlook actively want mail from legitimate high-volume senders. They optimize to avoid false positives for known, trusted senders. This is relationship-building, not "reputation scores."

04

ESP reputation affects only what they control.

An ESP's sending practices affect their shared IP reputation. But your domain's reputation is independent. You can have excellent domain reputation on a compromised IP, or poor reputation on a pristine one.

Recipient-Level Signals

Each recipient's relationship with your domain is built on their individual behavior:

Opens
Recipient actively reads your emails—strong positive signal
Clicks
Even stronger—they're engaging with your content
Replies
The strongest signal—this is a real conversation
Ignores
Unopened emails accumulate—relationship weakens over time
Spam Complaints
Catastrophic—one complaint damages more than 100 opens can repair
Strategic Implications
  • "List cleaning" is the wrong framing. You're not cleaning a list—you're managing individual relationships. Every recipient who ignores your emails is actively damaging the aggregate.
  • Monitor engagement at the individual level. Most systems only show aggregate metrics. Build systems that track per-recipient engagement and act on it.
  • Remove disengaged recipients aggressively. Someone who hasn't opened in 6 months isn't "on your list"—they're hurting your ability to reach everyone else.
  • One spam complaint is catastrophic. It's not just one data point—it's a recipient explicitly telling Gmail "this sender shouldn't reach me." That signal is weighted heavily.
  • Re-engagement campaigns are backwards. Sending more email to people who aren't engaging doesn't rebuild the relationship—it accelerates the damage.