Sender Reputation

Every time you send, mailbox providers watch what happens: do recipients open and reply, or mark it as spam? Does your mail hit dead addresses and spam traps, or clean ones? Over thousands of sends they distil this into a reputation, a running judgement of how trustworthy your mail is. That score, more than any other factor, decides whether your next message lands in the inbox, the spam folder, or is rejected at the door.

Reputation is not one number. Providers score your sending IP and your domain separately, and each provider keeps its own view, so you can sit well with Gmail and poorly with Microsoft at the same time. Domain reputation increasingly matters most, because it follows you even when you change IPs, which is why a consistently authenticated domain is the asset worth protecting.

Reputation is the sum of signals, weighted heavily toward how recipients react to you:

• Spam-complaint rate. The most damaging signal. Complaints above 0.3% mark you as a problem sender; the practical target is nearer 0.1%.
• Bounce rate. A high bounce rate, especially hard bounces, signals a dirty list and erodes trust fast.
• Engagement. Opens, clicks, and replies lift reputation; mail that is ignored or deleted unread pulls it down.
• Authentication. Aligned SPF, DKIM, and DMARC are the baseline; without them, reputation barely accrues.
• List hygiene and spam traps. Hitting spam traps or mailing unengaged addresses signals poor list hygiene and can trigger a sharp drop.
• Volume and consistency. Sudden spikes from a cold IP look like a compromised account; steady, warmed sending looks legitimate.

You cannot read a provider’s internal score directly, but several windows expose it. Google Postmaster Tools shows your Gmail spam rate and compliance status, though Google retired its old Bad/Low/Medium/High reputation grades in late 2025. A feedback loop reports complaints from providers that offer one. Third-party reputation services and blacklist checks fill in the rest of the picture.

For a fast, consolidated read across authentication, DNS, and blacklist status, run your domain through the sender reputation checker, which returns an A to F reputation score. The sender reputation guide walks through what each signal means and how to act on it.

Reputation is slow to build and quick to lose, so the work is preventive. Warm new IPs and domains gradually, send only to people who asked and still engage, suppress hard bounces on the first failure, keep complaints near zero, and authenticate everything. A single bad campaign to a stale list can undo months of careful sending.

Recovering a damaged reputation is harder than protecting a good one. It means cutting back to your most engaged recipients, fixing the root cause (a bad list, a broken unsubscribe, a compromised account), and rebuilding volume slowly while the provider re-learns that your mail is wanted. There is no reset button, only patient, clean sending over weeks.