Affected: npm: nodemailer

### Summary

Nodemailer's `disableFileAccess` / `disableUrlAccess` options are a security sandbox that lets an application forbid untrusted message content (`html`/`text`/attachment `path`/`href`) from reading local files or making outbound HTTP(S) requests. The fix for GHSA-wqvq-jvpq-h66f (commit `5f69497`) threaded these flags through the library's internal resolution paths (`MailMessage.resolveAll()` and `_convertDataImages()`), but the public plugin API `MailMessage.resolveContent(...args)` (`lib/mailer/mail-message.js:41-43`) remains a raw passthrough to `shared.resolveContent()`.

When called with the documented legacy signature `mail.resolveContent(data, key, callback)`, `shared.resolveContent` normalizes the missing options argument to an empty object (`options = options || {}`, `lib/shared/index.js:530`). The message-level flags that the `MailMessage` constructor already copied into `mail.data` (`lib/mailer/mail-message.js:34-38`) are silently discarded, so `resolveContentValue` skips both access-control guards and reaches `nmfetch(url)` (SSRF, `lib/shared/index.js:588`) or `fs.createReadStream(path)` (arbitrary file read, `lib/shared/index.js:597`).

A plugin or application code that resolves message content through the documented API (the same API the library's own `_convertDataImages` uses, threading the flags explicitly) thereby bypasses the sandbox an application deliberately enabled.

### Details

Root cause. The `MailMessage` constructor stores the transporte…