Email address spans

email-address-spans · version 1.0.0 · Communications · free, no key needed

Locate every email address occurrence in text with exact half-open code point, UTF-16 and UTF-8 offsets.

Use when you need to: find email address positions in text · character offsets of each email in a string · highlight email addresses with start and end index.

Decide before calling

Read the versioned contract and the supported scope below. Reuse email-address-spans@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use email-address-spans@1.0.0 for find email address positions in text. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• find email address positions in text
• character offsets of each email in a string
• highlight email addresses with start and end index
• annotate every email mention with its span
• redact emails by exact offsets
• utf-8 byte offsets of email addresses in text
• מיקום כתובות אימייל בטקסט

Not supported

• redact or rewrite the text itself
• deduplicate occurrences (use email-addresses-extract)
• parse display names, comments or group syntax
• verify that an address exists or accepts mail

Behavior

• Uses exactly the email-addresses-extract scanner: dot-atom local-part, "@", at least two ASCII LDH labels; left to right, non-overlapping; failing candidates are skipped, never shortened.
• Every occurrence is returned in text order, duplicates included. Offsets are half-open [start, end): start/end count Unicode code points, utf16_start/utf16_end count UTF-16 code units, utf8_start/utf8_end count UTF-8 bytes.
• text is the exact source substring at the span; address is its normalized form (local-part NFC with case preserved, domain ASCII-lowercased), so text and address differ only by normalization.
• Symmetric wrappers (' ` * _ ~ { }) and trailing dots are outside the span; angle brackets, quotes, commas and parentheses are boundaries.
• More than 65536 UTF-8 bytes of text, or more than 256 occurrences, is limit_exceeded; empty text returns an empty list. Unicode classes and NFC come from the runtime Unicode version.

Input

• text (string, required): Free text to scan (at most 65536 UTF-8 bytes).

Output

• spans (array of object, required): max items 256
• count (integer, required): min 0; max 256

Limits

• max text bytes: 65536
• max occurrences: 256

Example

Request input:

{
  "text": "Cc: <boss@nil.test>, sysservices@example.net"
}

Response:

{
  "result": {
    "spans": [
      {
        "text": "boss@nil.test",
        "address": "boss@nil.test",
        "start": 5,
        "end": 18,
        "utf16_start": 5,
        "utf16_end": 18,
        "utf8_start": 5,
        "utf8_end": 18
      },
      {
        "text": "sysservices@example.net",
        "address": "sysservices@example.net",
        "start": 21,
        "end": 44,
        "utf16_start": 21,
        "utf16_end": 44,
        "utf8_start": 21,
        "utf8_end": 44
      }
    ],
    "count": 2
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "email-address-spans",
  "version": "1.0.0",
  "input": {
    "text": "Cc: <boss@nil.test>, sysservices@example.net"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/email-address-spans/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"text":"Cc: <boss@nil.test>, sysservices@example.net"}'

The machine-readable contract is at /v1/tools/email-address-spans/versions/1.0.0.

CLI

node cli.mjs run email-address-spans 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Email addresses extract: Extract the unique email addresses (RFC 5322 addr-spec subset) from text, normalized, in first-seen order.
• Email address list parse: Parse an RFC 5322 address-list into ordered mailboxes, groups, and a canonical form.
• Email address list deduplicate: Drop duplicate mailboxes in an RFC 5322 address-list, keeping the first one.
• Email address list validate: Check RFC 5322 address-list syntax, including dots, quotes, comments, and groups.
• Email address list format: Format mailboxes and groups as one deterministic RFC 5322 address-list.
• Email address normalize: Validate one email addr-spec and return its canonical form: minimal quoting, NFC local-part, lowercase domain.