Billionmail/BillionMail · error

Prefix validation error: %w

Error message

Prefix validation error: %w

What it means

Thrown by BatchAdd when regexp.MatchString fails while validating the mailbox prefix against ^[\w-]+$. MatchString only errors on an invalid regular expression, which here is a compile-time constant, so in practice this error is nearly unreachable and always indicates an internal/regexp-engine problem rather than bad user input.

Source

Thrown at core/internal/service/mail_boxes/mail_boxes.go:255

	for i := range password {
		password[i] = charset[rand.Intn(len(charset))]
	}
	return string(password)
}
func BatchAdd(ctx context.Context, domain string, quota int, count int, prefix string, quotaActive int) ([]string, error) {

	if prefix == "" {
		randomPre := make([]byte, 4)
		for j := 0; j < 4; j++ {
			randomPre[j] = byte(rand.Intn(26) + 97) // a-z的ASCII码
		}

		prefix = string(randomPre)
	}

	matched, err := regexp.MatchString(`^[\w-]+$`, prefix)
	if err != nil {
		return nil, fmt.Errorf("Prefix validation error: %w", err)
	}
	if !matched {
		return nil, fmt.Errorf("Prefixes can contain only letters, numbers, underscores, and hyphens")
	}

	rand.Seed(time.Now().UnixNano())

	createdEmails := make([]string, 0, count)

	timestamp := time.Now().Unix()

	//passwordEncoded := PasswdEncode(ctx, password)
	//passwordCrypted, err := PasswdMD5Crypt(ctx, password)
	//if err != nil {
	//	return nil, fmt.Errorf("Generate password md5-crypt failed: %w", err)
	//}

	mailboxes := make([]v1.Mailbox, 0, count)

View on GitHub (pinned to fc36c76c05)

Solutions

1. Confirm the regex literal ^[\w-]+$ in mail_boxes.go was not modified to an invalid pattern
2. Check the wrapped error from %w for the exact regexp compile message
3. Rebuild/redeploy the binary with an unmodified, supported Go toolchain

if err != nil && strings.Contains(err.Error(), "Prefix validation error") {
    // internal regexp failure: report as a bug, do not retry blindly
}

When it happens

Trigger: Calling BatchAddMailbox (via BatchAdd) and the Go regexp engine fails to compile/match the hard-coded pattern ^[\w-]+$ during prefix validation.

Common situations: Extremely rare; could occur with a corrupted Go installation, a modified copy of the code where the pattern string is built dynamically and contains invalid regex syntax, or exotic regexp-engine edge cases.

Related errors

• Add up to 3 URLs
• supplier name, base URL, and API key are required
• invalid base URL format: %w
• base URL must use http or https protocol
• Prefixes can contain only letters, numbers, underscores, and

AI-assisted analysis of Billionmail/BillionMail@fc36c76c05 (2026-09-05). Data as JSON: /api/errors/14cd082610740ed1. Report an issue: GitHub.