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feat: configurable sub-addressing delimiter #239

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This commit is contained in:
Linus Rath
2026-05-01 01:42:06 +02:00
parent a8db02e881
commit c555973b6b
23 changed files with 252 additions and 41 deletions
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lib/sub-addressing.ts
+36 -14
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@@ -1,12 +1,23 @@
/**
* Sub-addressing utilities for user+tag@domain.com format
* Sub-addressing utilities for user{delimiter}tag@domain.com format
* Works server-side automatically - no JMAP API calls needed
*
* The delimiter character is configurable per server (RFC 5233). Common
* choices: "+" (Postfix, Stalwart default), "-" (qmail), ".", "=".
*/
// Constants for tag validation
const MAX_TAG_LENGTH = 30;
const TAG_REGEX = /^[a-zA-Z0-9-]{1,30}$/;
export const DEFAULT_SUB_ADDRESS_DELIMITER = '+';
export const SUPPORTED_SUB_ADDRESS_DELIMITERS = ['+', '-', '.', '='] as const;
export type SubAddressDelimiter = (typeof SUPPORTED_SUB_ADDRESS_DELIMITERS)[number];
export function isSupportedSubAddressDelimiter(value: string): value is SubAddressDelimiter {
return (SUPPORTED_SUB_ADDRESS_DELIMITERS as readonly string[]).includes(value);
}
export type TagValidationErrorCode =
| 'EMPTY'
| 'TOO_LONG'
@@ -22,10 +33,14 @@ export interface ParsedAddress {
}
/**
* Parse an email address to extract sub-address tag
* Example: "user+shopping@example.com" -> { baseUser: "user", tag: "shopping" }
* Parse an email address to extract sub-address tag.
* The first occurrence of the delimiter in the local part separates the
* base user from the tag, matching the behavior of Postfix/qmail/Sieve.
*/
export function parseSubAddress(email: string): ParsedAddress {
export function parseSubAddress(
email: string,
delimiter: string = DEFAULT_SUB_ADDRESS_DELIMITER,
): ParsedAddress {
const [localPart, domain] = email.split('@');
if (!localPart || !domain) {
@@ -38,9 +53,9 @@ export function parseSubAddress(email: string): ParsedAddress {
};
}
const plusIndex = localPart.indexOf('+');
const delimiterIndex = localPart.indexOf(delimiter);
if (plusIndex === -1) {
if (delimiterIndex === -1) {
return {
localPart,
baseUser: localPart,
@@ -50,8 +65,8 @@ export function parseSubAddress(email: string): ParsedAddress {
};
}
const baseUser = localPart.substring(0, plusIndex);
const tag = localPart.substring(plusIndex + 1);
const baseUser = localPart.substring(0, delimiterIndex);
const tag = localPart.substring(delimiterIndex + delimiter.length);
return {
localPart,
@@ -63,18 +78,25 @@ export function parseSubAddress(email: string): ParsedAddress {
}
/**
* Generate a sub-addressed email
* Example: generateSubAddress("user@example.com", "shopping") -> "user+shopping@example.com"
* Generate a sub-addressed email.
* Example: generateSubAddress("user@example.com", "shopping", "+") -> "user+shopping@example.com"
*/
export function generateSubAddress(baseEmail: string, tag: string): string {
export function generateSubAddress(
baseEmail: string,
tag: string,
delimiter: string = DEFAULT_SUB_ADDRESS_DELIMITER,
): string {
const [localPart, domain] = baseEmail.split('@');
if (!localPart || !domain || !tag) {
return baseEmail;
}
// Remove existing tag if present
const cleanLocal = localPart.split('+')[0];
// Strip an existing tag if one is already present
const existingDelimiterIndex = localPart.indexOf(delimiter);
const cleanLocal = existingDelimiterIndex === -1
? localPart
: localPart.substring(0, existingDelimiterIndex);
// Sanitize tag (alphanumeric and dash only)
const cleanTag = tag.replace(/[^a-zA-Z0-9-]/g, '').toLowerCase();
@@ -83,7 +105,7 @@ export function generateSubAddress(baseEmail: string, tag: string): string {
return baseEmail;
}
return `${cleanLocal}+${cleanTag}@${domain}`;
return `${cleanLocal}${delimiter}${cleanTag}@${domain}`;
}
/**