Also known as: Sender Score, Domain Reputation
A trust score that mailbox providers assign to your sending IP and domain, which determines whether your mail reaches the inbox.
Sender reputation is the running judgment mailbox providers form about you, attached to both your sending IP address and your domain. It is built from signals like your bounce rate, complaint rate, spam-trap hits, and how recipients engage with your mail. The better your reputation, the more of your mail reaches the inbox.
Reputation is slow to build and quick to lose. A single campaign to a dirty list — full of dead addresses and traps — can damage standing that took months to earn, and recovery is gradual. This is the core reason to verify before you send.
BounceShift also turns reputation into a verification signal: with consent, real bounce and delivery outcomes from connected mail streams (stored only as one-way hashes) feed back into scoring, so the engine learns which addresses and domains genuinely deliver.
The percentage of sent emails that could not be delivered and were returned by the receiving server.
The percentage of recipients who mark your email as spam, a key signal mailbox providers use to judge senders.
The ability of your email to actually reach recipients' inboxes rather than being blocked or filtered to spam.
An email address used by mailbox providers and blocklists to identify senders with poor list hygiene.
See it in action
Check any address against BounceShift's multi-layer engine — syntax, MX, disposable, and role checks free, with full SMTP verification on signup.