Email address list format

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

Format mailboxes and groups as one deterministic RFC 5322 address-list.

Use when you need to: format an rfc 5322 address list · render structured mailboxes as a recipient list · write a canonical to header from mailboxes and groups.

Decide before calling

Read the versioned contract and the supported scope below. Reuse email-address-list-format@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-list-format@1.0.0 for format an rfc 5322 address list. 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

• format an rfc 5322 address list
• render structured mailboxes as a recipient list
• write a canonical to header from mailboxes and groups
• quote a display name for an address list
• serialize groups and addr-specs
• build an address list from mailbox parts

Not supported

• parse free-form header text
• remove duplicate recipients
• send the formatted header

Behavior

• Dot-atom-text is 1*atext *("." 1*atext) per RFC 5322 section 3.2.3, used by section 3.4.1. U+002E is not atext. A leading dot, a trailing dot, or two dots in a row is rejected in a local-part and in a domain, in both ascii and utf-8 modes. Inside a domain-literal or a quoted-string, a dot is ordinary text.
• mode ascii accepts only Unicode scalar values U+0000 through U+007F. mode utf-8 also treats U+0080 through U+10FFFF as atext, qtext, ctext, dtext and VCHAR, which is the RFC 6532 section 3.2 extension. The dot separator stays U+002E only.
• Canonical form drops comments and folding white space. A local-part that is a dot-atom is written unquoted; any other local-part is a quoted-string. A display name that is atoms separated by one space is written unquoted; otherwise it is a quoted-string. A mailbox with no display name is a bare addr-spec. Top-level addresses are joined by a comma and one space. Group members are joined by a comma with no space, with no space around the colon, and an empty group is name:; .
• A domain that is not a dot-atom or a domain-literal, including a leading, trailing, or doubled dot, is invalid_input. A local-part that is not a dot-atom is quoted rather than rejected.
• The same structured input always produces the same text. No clock, locale, or network.
• Disclaimer: format transform only; provides no confidentiality, integrity, or authenticity.

Input

• mode (one of "ascii", "utf-8", required)
• addresses (array of object or object, required): min items 1; max items 32

Output

• mode (one of "ascii", "utf-8", required)
• text (string, required): min length 1; max length 8192
• address_count (integer, required): min 1; max 32
• mailbox_count (integer, required): min 0; max 32
• group_count (integer, required): min 0; max 32

Limits

• max input bytes: 4096
• max addresses: 32
• max groups: 32
• max output bytes: 65536

Example

Request input:

{
  "mode": "ascii",
  "addresses": [
    {
      "kind": "mailbox",
      "display_name": "Mary Smith",
      "local_part": "mary",
      "domain": "x.test"
    }
  ]
}

Response:

{
  "result": {
    "mode": "ascii",
    "text": "Mary Smith <mary@x.test>",
    "address_count": 1,
    "mailbox_count": 1,
    "group_count": 0
  }
}

How to call it

MCP

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

{
  "id": "email-address-list-format",
  "version": "1.0.0",
  "input": {
    "mode": "ascii",
    "addresses": [
      {
        "kind": "mailbox",
        "display_name": "Mary Smith",
        "local_part": "mary",
        "domain": "x.test"
      }
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/email-address-list-format/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"mode":"ascii","addresses":[{"kind":"mailbox","display_name":"Mary Smith","local_part":"mary","domain":"x.test"}]}'

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

CLI

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

Get the client at /clients/cli/.

Related tools

• Email address list parse: Parse an RFC 5322 address-list into ordered mailboxes, groups, and a canonical form.
• Email mailbox format: Render a canonical RFC 5322 mailbox from decoded parts, without a delivery claim.
• Email address list deduplicate: Drop duplicate mailboxes in an RFC 5322 address-list, keeping the first one.
• Email mailbox parse: Parse one RFC 5322 mailbox into parts and canonical text, without a delivery claim.
• Email address list validate: Check RFC 5322 address-list syntax, including dots, quotes, comments, and groups.
• Email mailbox validate: Check one RFC 5322 mailbox for syntax only and return a stable reason code.