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Sender Reputation: The Score That Decides Your Inbox Fate

What sender reputation is, what drives it up or down, and how to build and protect it over time.

Dmitry Korolev
Founder, deliverability
March 27, 20266 min read

Sender reputation is the trust score mailbox providers assign to your domain and IP. It is the single biggest factor in whether you reach the inbox — content barely matters if reputation is poor.

What drives it

  • Complaint rate — keep it well under 0.1%.
  • Bounce rate — clean lists, remove dead addresses.
  • Engagement — opens, clicks and replies raise it; ignores lower it.
  • Authentication — SPF, DKIM, DMARC must pass.
  • Consistency — steady volume beats erratic spikes.
Sendersy

Send email that actually lands in the inbox

API and visual editor, SPF/DKIM/DMARC out of the box, analytics and warm IPs. Free tier — 200 emails/month, no card required.

It is domain and IP based

Both your domain and sending IP carry reputation. A warm shared pool inherits a managed IP reputation; your domain reputation you build yourself through good sending habits.

Recovering a damaged reputation

It is slow. Stop bad sending, prune to your most engaged contacts, and rebuild volume gradually — exactly like a fresh warm-up.

Protect it from day one

Sendersy manages IP reputation and surfaces complaint and bounce signals early so you act before damage spreads. Start free.

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Written by
Dmitry Korolev
Founder, deliverability

Builds the Sendersy sending stack. Ten years deep in deliverability, SPF/DKIM/DMARC and IP reputation.