TL;DR
- Reputation attaches to your sending domain and IP address, not to one campaign or one salesperson.
- Bounces, spam complaints, spam traps and blocklist listings push it down; authenticated, wanted, low-bounce mail builds it.
- When it drops, all mail from that domain suffers, including mail to existing customers.
- It's slow to rebuild. Prevention (clean lists, authentication) is cheaper than repair.
Domain vs IP reputation
IP reputation follows the address your mail leaves from; on shared sending infrastructure other senders' behaviour can affect you. Domain reputation follows the domain in your From address and your authentication records, and it travels with you across IPs and tools. Mailbox providers use both. Google's Postmaster Tools reports domain and IP reputation for senders who verify their domain with it.
What moves it
| Signal | Direction | Within your control? |
|---|---|---|
| Hard bounces (dead addresses) | Down | Yes: verify lists |
| Spam complaints | Down | Yes: send to people who want it, make unsubscribing easy |
| Spam trap hits | Down | Yes: avoid old and scraped lists |
| Blocklist listings | Down | Indirectly: they follow the signals above |
| SPF, DKIM and DMARC alignment | Up when correct | Yes: check yours |
| Engagement (opens, replies) | Up | Partly |
Gmail's sender guidelines set a spam-complaint ceiling of 0.30% in Postmaster Tools, and stricter requirements apply to bulk senders; see Gmail and Yahoo bulk sender requirements.
Why it hurts everyone
Because reputation belongs to the sender, a bad list affects every message from that domain: follow-ups, invoices, renewal reminders and support replies. See how blocklists work for how a single listing can switch delivery off without a warning.
How to protect it
- Authenticate every sending domain (SPF, DKIM, DMARC).
- Verify every list before sending and keep bounces under 2%.
- Use separate domains for cold outreach so a problem never touches your main domain. Checklist.
- Remove addresses that complain or hard-bounce immediately.
- Watch Postmaster Tools and bounce rates weekly.
If it's damaged
Stop sending to the cause, fix it, then ramp volume slowly. See recovering a burned domain.
FAQ
What is sender reputation?
A score mailbox providers keep for your domain and sending IP, based on how recipients and servers respond to your mail.
How do I check my sender reputation?
Google Postmaster Tools for Gmail, plus your sending platform's bounce reports and blocklist lookups.
How long does it take to recover sender reputation?
It varies with how deep the damage is; treat it as weeks of careful sending, not a quick fix.
Instantly
Smartlead
HubSpot
Mailchimp
Apollo
Zapier
Google Sheets
Make