tmailrDeliverability
Sending reputation is per IP and per domain, and they are not the same
14 July 2026 · 2 min read · TMailr
Sender reputation is discussed as though it were one score. It is at least two, they move at different speeds, and knowing which one you have damaged tells you whether to wait a week or change something.
The IP reputation
Attached to the address you connect from. It responds quickly, in both directions: a bad day of complaints hurts within hours, and consistent good behaviour repairs it in days.
On a shared platform you inherit it from everyone else on that IP, which is fine when the platform polices its customers and painful when it does not. A dedicated IP gives you control and an obligation: an unwarmed dedicated IP sending fifty thousand messages on its first day looks exactly like a compromised host, because that is the traffic pattern of one.
The domain reputation
Attached to the domain in your From: header and increasingly to the domain that signed with DKIM. It moves slowly, it survives changing platforms, and it is the one that really matters, because it is the one you own.
This is the reason to authenticate with your own domain rather than your platform’s. Mail signed by your platform builds their reputation. Mail signed by yours builds an asset you keep when you move.
Why the distinction is practical
- Deliverability dropped after changing platform, and the content did not change: IP reputation, and it will recover as the new addresses warm.
- Deliverability dropped and the sending IPs did not change: look at your list and your content, because that is domain reputation.
- Only one provider is affected: their filter, and their postmaster tools will usually say why.
- Everything is affected at once: something structural, usually authentication or a blocklist.
Separate what you cannot afford to lose
Send transactional mail and marketing mail from different subdomains, each with its own DKIM key. A campaign that generates complaints then damages the subdomain it was sent from, and password resets keep arriving.
It also gives you a clean signal. When receipts are fine and campaigns are not, you know it is the campaigns rather than your domain, which is the difference between a content problem and an emergency.
Repairing either
There is no appeal that works faster than behaving well. Reduce volume, send only to people who recently engaged, fix whatever generated the complaints, and be patient. IP reputation returns in days. Domain reputation takes weeks, which is why the advice is always to protect it rather than repair it.
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