Deliverability
Updated
Sender reputation
Definition
Sender reputation is the trust score mailbox providers assign to your sending domain and IP addresses, based on how recipients and their systems react to your mail. It is the biggest single factor in whether you reach the inbox.
How it works
Providers track reputation per authenticated domain (the DKIM d= domain and From domain) and per sending IP. Domain reputation follows you across ESPs. IP reputation belongs to whoever sends from that IP, which on shared infrastructure includes other senders.
Negative signals: spam complaints, sending to non-existent addresses, spam trap hits, sudden volume spikes, and failed authentication. Positive signals: opens, replies, moving mail out of spam, adding you to contacts.
Reputation is computed over a rolling window, so it reflects your recent behavior. A bad week can take weeks of good sending to repair.
Example
A domain sending like this builds reputation. Double the complaints and it starts to slide.
Why it matters
With a good reputation, filters give your mail the benefit of the doubt. With a poor one, even perfect content goes to spam, and providers may throttle or reject your traffic.
Because domain reputation follows your domain, switching ESPs does not reset it. Fixing the list and the sending habits does.
Best practices
- Authenticate with your own domain so you build reputation you control.
- Register your domain in Google Postmaster Tools and watch the spam rate. Microsoft's SNDS shows data for dedicated IPs.
- Send to engaged subscribers first, and stop mailing people who have not opened or clicked in months.
- Avoid sudden volume jumps. Ramp up new domains and IPs gradually.
- Never buy, rent or scrape lists. They contain spam traps and people who will report you.
How Lumail handles sender reputation
Lumail sends from your own authenticated domain, so the reputation you build is attached to your brand. Its sender score (0-100) reflects the last 30 days of bounces, complaints, opens and clicks and appears as Sender health in Settings, Deliverability.
Guardrails protect that reputation: permanent bounces and complaints are suppressed, per-recipient rate guards stop one address from being flooded, and alerts fire when bounce or complaint rates stay elevated.
Check a real message with the free mail tester or the spam tester.
Frequently asked questions
Is domain reputation or IP reputation more important?
For most senders today, domain reputation. Gmail and other large providers lean heavily on the authenticated domain, and it follows you if you change IPs or providers.
How do I check my sender reputation?
Use Google Postmaster Tools for Gmail spam rate and compliance, Microsoft SNDS for IP data, and your ESP's bounce, complaint and engagement metrics per send.
How long does it take to fix a bad sender reputation?
Usually weeks, because providers score a rolling window. Cut sending to unengaged and unconfirmed contacts, fix authentication, and send consistently to your most engaged subscribers while it recovers.
Related terms, tools and docs
- DeliverabilityEmail deliverabilityEmail deliverability is the ability of your emails to reach recipients' inboxes rather than bouncing or landing in spam.
- MetricsSpam complaint rateSpam complaint rate is the percentage of delivered emails that recipients reported as spam.
- DeliverabilityEmail warmupEmail warmup is the practice of gradually increasing sending volume from a new domain or IP address so mailbox providers can build a positive reputation for it before you send at full volume..
- List managementList hygieneList hygiene is the routine of removing or suppressing email addresses that hurt deliverability: hard bounces, spam complainers, long-inactive subscribers, invalid addresses and likely spam traps..
- Free toolFree mail testerSend a real email and get an SPF, DKIM, DMARC and content report.
- Free toolFree spam testerCheck an email for the patterns that push mail to spam.
- DocsSender healthHow Lumail measures sending health and authentication.
- DocsAccount verificationHow sending unlocks when your domain verifies.
- DocsRecipient rate guardsPer-address caps and bounce cooldowns.
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