Email Reputation

The Email Reputation endpoints provide sending IP reputation scoring based on trap hits, blocklist status, telemetry signals, and behavioral analysis. Scores range from 0 (worst) to 100 (best). Single-IP and batch reputation routes are anonymous, expose only LimesIndex-owned evidence, and share a 60 requests/minute per-client-IP limit.

Single IP Reputation

GET /v1/email/ip/{ip}/reputation

Get the full sending reputation for an IP, including contributing factors, 30-day history, and subnet context.

Path Parameters

Parameter	Type	Required	Description
`ip`	string	Yes	IPv4 or IPv6 address

Response (200)

{
  "data": {
    "ip": "198.51.100.25",
    "score": 71,
    "level": "neutral",
    "factors": [
      {
        "name": "ip_age_days",
        "impact": 6,
        "detail": "Observed sending for 95 days (+2 per 30 days, capped at +20)"
      },
      {
        "name": "neighbor_reputation",
        "impact": 10,
        "detail": "Subnet 198.51.100.0/24 is clean — no active listings"
      },
      {
        "name": "datacenter_type",
        "impact": 5,
        "detail": "Active dataset classifies this IP as a datacenter with no negative reputation signals"
      }
    ],
    "history": [
      {
        "score": 75,
        "level": "good",
        "computed_at": "2026-04-12T00:00:00Z"
      },
      {
        "score": 72,
        "level": "good",
        "computed_at": "2026-04-11T00:00:00Z"
      }
    ],
    "subnet": {
      "subnet": "198.51.100.0/24",
      "total_ips_seen": 12,
      "listed_count": 0,
      "avg_reputation": 71,
      "worst_score": 71,
      "contamination_level": "clean"
    },
    "blocklist": {
      "listed": false
    },
    "fcrdns": {
      "ip": "198.51.100.25",
      "ptr_hostname": "mail.example.net",
      "forward_match": true,
      "forward_ips": ["198.51.100.25"],
      "last_checked_at": "2026-04-12T00:00:00Z",
      "last_observed_at": "2026-04-12T00:00:00Z"
    }
  },
  "meta": {
    "processing_time_ms": 12
  }
}

Response Fields

Data Object

Field	Type	Description
`ip`	string	The queried IP address (normalized)
`score`	integer	Reputation score (0-100)
`level`	string	Human-readable level
`factors`	array	Factors contributing to the score
`history`	array	30-day score history
`subnet`	object	Subnet reputation context
`blocklist`	object	LimesIndex-owned blocklist status
`fcrdns`	object	Latest FCrDNS status, when available

Factor Object

Field	Type	Description
`name`	string	Factor identifier
`impact`	integer	Positive or negative impact on the score
`detail`	string	Human-readable explanation

History Point

Field	Type	Description
`score`	integer	Score at that point
`level`	string	Level at that point
`computed_at`	string	ISO 8601 timestamp

Score Ranges

Score	Level	Description
80-100	good	Healthy sender reputation
60-79	neutral	Some risk signals detected
40-59	poor	Multiple negative signals
0-39	bad	Severe reputation issues

Scoring model

The scorer is deterministic and starts at 50 (neutral/unknown). Each returned factor explains its exact contribution; the final score is clamped to 0–100.

The production factors are:

active blocklist listing: −40;
pristine trap hits: −15 per hit, capped at −45;
recycled/typo trap hits: −5 per hit, capped at −20;
SMTP honeypot activity: −15;
cross-signal corroboration: −10 per additional signal type, capped at −30;
telemetry_bounce_rate above 5%: −25;
telemetry_complaint_rate above 0.1%: −30;
a clean /24 subnet: +10;
repeated historical listings (three or more in 30 days): −10;
geo instability: −10 for one or two changes, −20 for three or more;
failed FCrDNS: −15;
earliest production observation age: +2 per 30 full days, capped at +20;
active datacenter classification: +5 only when no negative reputation signal is present.

The neighbor_reputation factor feeds back the subnet result for IPv4 addresses: clean is +10, light contamination is 0, moderate is −5, and heavy is −15. The neighbors endpoint reports clean for zero active listings, light for 1–2, moderate for 3–5, and heavy for 6 or more.

An absent age or datacenter classification is unknown and contributes no bonus. Synthetic trap observations are excluded from the age anchor and all production reputation evidence. Evidence read failures are returned as an unavailable error rather than converted into a neutral or clean score.

Batch Reputation

POST /v1/email/reputation/batch

Get reputation scores for multiple IPs in a single request. Returns score and level for each IP.

Request Body

{
  "ips": ["198.51.100.25", "203.0.113.50"]
}

Maximum 100 IPs per request.

Response (200)

{
  "data": [
    {
      "ip": "198.51.100.25",
      "score": 78,
      "level": "good"
    },
    {
      "ip": "203.0.113.50",
      "score": 50,
      "level": "neutral"
    }
  ],
  "meta": {
    "processing_time_ms": 20
  }
}

Limits

Maximum 100 IPs per request
Invalid or non-public IPs are rejected with 400 Bad Request.
If reputation evidence is unavailable for an IP, the request returns 503 rather than synthesizing a neutral score.

Subnet Neighbors

GET /v1/email/ip/{ip}/neighbors

Analyze the /24 subnet reputation around an IP address. Shows how many neighbors are listed and the overall contamination level. Useful for understanding whether an IP is in a "bad neighborhood."

Path Parameters

Parameter	Type	Required	Description
`ip`	string	Yes	Public IPv4 address

Response (200)

{
  "data": {
    "subnet": "198.51.100.0/24",
    "total_ips_seen": 12,
    "listed_count": 1,
    "avg_reputation": 65,
    "worst_score": 30,
    "contamination_level": "light"
  },
  "meta": {
    "processing_time_ms": 8
  }
}

Response Fields

Field	Type	Description
`subnet`	string	The /24 subnet in CIDR notation
`total_ips_seen`	integer	Total IPs observed in this subnet
`listed_count`	integer	Number of active blocklist listings in this subnet
`avg_reputation`	integer	Average reputation score in the subnet
`worst_score`	integer	Lowest reputation score in the subnet
`contamination_level`	string	Overall level: clean, light, moderate, heavy

Contamination Levels

Level	Description
clean	No blocklisted IPs in the subnet
light	1-2 listed IPs, low risk to neighbors
moderate	Multiple listed IPs, some risk of guilt-by-association
heavy	Many listed IPs, significant shared-IP risk

Error Responses

400 Bad Request

{
  "data": {
    "error": "invalid IP address",
    "code": "INVALID_IP"
  },
  "meta": {
    "processing_time_ms": 0
  }
}

Code Examples

cURL

# Single IP reputation (anonymous; 60 requests/minute per client IP)
curl "https://api.limesindex.com/v1/email/ip/198.51.100.25/reputation"

# Batch reputation (anonymous; shares the same 60 requests/minute budget)
curl -X POST "https://api.limesindex.com/v1/email/reputation/batch" \
  -H "Content-Type: application/json" \
  -d '{"ips": ["198.51.100.25", "203.0.113.50"]}'

# Subnet neighbors
curl -X GET "https://api.limesindex.com/v1/email/ip/198.51.100.25/neighbors" \
  -H "X-API-Key: YOUR_API_KEY"

Python

import requests

BASE_URL = "https://api.limesindex.com"

# Get reputation for an IP
resp = requests.get(
    f"{BASE_URL}/v1/email/ip/198.51.100.25/reputation"
)
data = resp.json()["data"]
print(f"Score: {data['score']} ({data['level']})")
for factor in data["factors"]:
    sign = "+" if factor["impact"] > 0 else ""
    print(f"  {sign}{factor['impact']} {factor['name']}: {factor['detail']}")

# Check subnet health
resp = requests.get(
    f"{BASE_URL}/v1/email/ip/198.51.100.25/neighbors",
    headers={"X-API-Key": "YOUR_API_KEY"}
)
subnet = resp.json()["data"]
print(f"Subnet: {subnet['subnet']}")
print(f"Contamination: {subnet['contamination_level']}")
print(f"Listed neighbors: {subnet['listed_count']}/{subnet['total_ips_seen']}")

Use Cases

Pre-campaign assessment: Check your sending IPs' reputation before a campaign
IP rotation decisions: Identify which IPs in your pool need rest or removal
Subnet risk: Understand shared-IP contamination risk before purchasing new IPs
Trend monitoring: Track reputation history to detect degradation early

Blocklist - Direct blocklist status checks
Warmup - Warm-up guidance based on reputation
Email Domain DNS - Domain authentication analysis

Single IP Reputation​

Path Parameters​

Response (200)​

Response Fields​

Data Object​

Factor Object​

History Point​

Score Ranges​

Scoring model​

Batch Reputation​

Request Body​

Response (200)​

Limits​

Subnet Neighbors​

Path Parameters​

Response (200)​

Response Fields​

Contamination Levels​

Error Responses​

400 Bad Request​

Code Examples​

cURL​

Python​

Use Cases​

Related Endpoints​

Single IP Reputation

Path Parameters

Response (200)

Response Fields

Data Object

Factor Object

History Point

Score Ranges

Scoring model

Batch Reputation

Request Body

Response (200)

Limits

Subnet Neighbors

Path Parameters

Response (200)

Response Fields

Contamination Levels

Error Responses

400 Bad Request

Code Examples

cURL

Python

Use Cases

Related Endpoints