Compose MIME independently of SMTP

.github/workflows/main.yaml

@@ -6,6 +6,19 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  test-edge:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        persist-credentials: false
+    - uses: jdx/mise-action@v4
+      with:
+        experimental: true
+        cache: true
+        cache_key_prefix: mise-v4
+    - run: mise run test:edge
+
   test-node:
     runs-on: ubuntu-latest
     env:
@@ -172,7 +185,7 @@ jobs:
 
   publish:
     if: github.event_name == 'push'
-    needs: [test-node, test-deno, test-bun, check]
+    needs: [test-node, test-deno, test-bun, test-edge, check]
     runs-on: ubuntu-latest
     permissions:
       contents: read

AGENTS.md

@@ -33,6 +33,7 @@ functions.  It's structured as a monorepo with multiple packages:
 *Repository*: <https://github.com/dahlia/upyo>
 
  -  *@upyo/core*: Shared types and interfaces for email messages
+ -  *@upyo/mime*: Portable MIME composition and DKIM signing
  -  *@upyo/smtp*: SMTP transport implementation
  -  *@upyo/lettermint*: Lettermint transport implementation
  -  *@upyo/logtape*: LogTape observability transport

CHANGES.md

@@ -229,6 +229,19 @@ To be released.
 [Mailtrap]: https://mailtrap.io/
 [#32]: https://github.com/dahlia/upyo/pull/32
 
+### @upyo/mime
+
+ -  Added *@upyo/mime* with `composeMessage()` for composing replayable MIME
+    bytes without a transport connection, with optional DKIM signing.  Save
+    the bytes as an *.eml* file or pass the result directly to SMTP or JMAP
+    `sendRaw()`.  The package supports Node.js, Deno, Bun, and edge runtimes
+    without Node.js compatibility.  Address line breaks and invalid custom
+    header names are rejected even for directly constructed messages.
+    [[#68], [#74]]
+
+[#68]: https://github.com/dahlia/upyo/issues/68
+[#74]: https://github.com/dahlia/upyo/pull/74
+
 ### @upyo/opentelemetry
 
  -  Fixed the `email.content.type` span attribute and the `content_type` metric
@@ -341,7 +354,8 @@ To be released.
     custom OAuth2 token provider, so cancelled operations release their
     connections promptly.
  -  Added automatic SMTPUTF8 delivery for internationalized sender, recipient,
-    and reply-to addresses.  Servers must advertise `SMTPUTF8` and `8BITMIME`;
+    and reply-to addresses, as well as internationalized nested MIME and DKIM
+    headers.  Servers must advertise `SMTPUTF8` and `8BITMIME`;
     unsupported sends fail without starting a mail transaction.  [[#45], [#50]]
  -  Added incremental SMTP attachment encoding and backpressured DATA writes.
     Set `dkim.bodyMode` to `"streaming"` for bounded attachment memory with two
@@ -402,6 +416,11 @@ To be released.
     465 uses implicit TLS; all other ports start with plaintext and upgrade with
     STARTTLS when advertised.  Set `secure: true` explicitly to use implicit
     TLS on a nonstandard port.  [[#53], [#55]]
+ -  Fixed quoted-printable encoding of CRLF, isolated line endings, trailing
+    spaces, and long lines so messages preserve their text and respect MIME
+    line limits.  Inline Content-ID headers now reject values that cannot fit
+    the RFC 5322 line limit.  Directly constructed messages now reject address
+    line breaks and invalid custom header names.  [[#68], [#74]]
 
 [#42]: https://github.com/dahlia/upyo/issues/42
 [#43]: https://github.com/dahlia/upyo/issues/43

README.md

@@ -67,6 +67,7 @@ sending messages.  The following is a list of the available packages:
 | Package                                         | JSR                            | npm                            | Description                                        |
 | ----------------------------------------------- | ------------------------------ | ------------------------------ | -------------------------------------------------- |
 | [@upyo/core](/packages/core/)                   | [JSR][jsr:@upyo/core]          | [npm][npm:@upyo/core]          | Shared types and interfaces for email messages     |
+| [@upyo/mime](/packages/mime/)                   | [JSR][jsr:@upyo/mime]          | [npm][npm:@upyo/mime]          | Portable MIME composition and DKIM signing         |
 | [@upyo/smtp](/packages/smtp/)                   | [JSR][jsr:@upyo/smtp]          | [npm][npm:@upyo/smtp]          | SMTP transport                                     |
 | [@upyo/jmap](/packages/jmap/)                   | [JSR][jsr:@upyo/jmap]          | [npm][npm:@upyo/jmap]          | [JMAP] transport (RFC 8620/8621)                   |
 | [@upyo/lettermint](/packages/lettermint/)       | [JSR][jsr:@upyo/lettermint]    | [npm][npm:@upyo/lettermint]    | [Lettermint] transport                             |
@@ -84,6 +85,8 @@ sending messages.  The following is a list of the available packages:
 
 [jsr:@upyo/core]: https://jsr.io/@upyo/core
 [npm:@upyo/core]: https://www.npmjs.com/package/@upyo/core
+[jsr:@upyo/mime]: https://jsr.io/@upyo/mime
+[npm:@upyo/mime]: https://www.npmjs.com/package/@upyo/mime
 [jsr:@upyo/smtp]: https://jsr.io/@upyo/smtp
 [npm:@upyo/smtp]: https://www.npmjs.com/package/@upyo/smtp
 [jsr:@upyo/jmap]: https://jsr.io/@upyo/jmap

changes.d/mime/mime-composition.md

@@ -0,0 +1,12 @@
+---
+links:
+  '#68': https://github.com/dahlia/upyo/issues/68
+  '#74': https://github.com/dahlia/upyo/pull/74
+---
+ -  Added *@upyo/mime* with `composeMessage()` for composing replayable MIME
+    bytes without a transport connection, with optional DKIM signing.  Save
+    the bytes as an *.eml* file or pass the result directly to SMTP or JMAP
+    `sendRaw()`.  The package supports Node.js, Deno, Bun, and edge runtimes
+    without Node.js compatibility.  Address line breaks and invalid custom
+    header names are rejected even for directly constructed messages.
+    [[#68], [#74]]

changes.d/smtp/mime-line-encoding.md

@@ -0,0 +1,10 @@
+---
+links:
+  '#68': https://github.com/dahlia/upyo/issues/68
+  '#74': https://github.com/dahlia/upyo/pull/74
+---
+ -  Fixed quoted-printable encoding of CRLF, isolated line endings, trailing
+    spaces, and long lines so messages preserve their text and respect MIME
+    line limits.  Inline Content-ID headers now reject values that cannot fit
+    the RFC 5322 line limit.  Directly constructed messages now reject address
+    line breaks and invalid custom header names.  [[#68], [#74]]

changes.d/smtp/smtputf8.md

@@ -4,5 +4,6 @@ links:
   '#50': https://github.com/dahlia/upyo/pull/50
 ---
  -  Added automatic SMTPUTF8 delivery for internationalized sender, recipient,
-    and reply-to addresses.  Servers must advertise `SMTPUTF8` and `8BITMIME`;
+    and reply-to addresses, as well as internationalized nested MIME and DKIM
+    headers.  Servers must advertise `SMTPUTF8` and `8BITMIME`;
     unsupported sends fail without starting a mail transaction.  [[#45], [#50]]