guicedee-mail-client
Annotation-driven SMTP mail client for GuicedEE with Vert.x 5: @MailConnectionOptions for SMTP server configuration, MailService injection for sending text/HTML/multipart emails with attachments, connection pooling, StartTLS/SSL support, DKIM signing, environment variable overrides, and graceful shutdown. Use when sending emails via SMTP, configuring mail connections, or injecting mail services.
Best use case
guicedee-mail-client is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Annotation-driven SMTP mail client for GuicedEE with Vert.x 5: @MailConnectionOptions for SMTP server configuration, MailService injection for sending text/HTML/multipart emails with attachments, connection pooling, StartTLS/SSL support, DKIM signing, environment variable overrides, and graceful shutdown. Use when sending emails via SMTP, configuring mail connections, or injecting mail services.
Teams using guicedee-mail-client should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/guicedee-mail-client/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How guicedee-mail-client Compares
| Feature / Agent | guicedee-mail-client | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Annotation-driven SMTP mail client for GuicedEE with Vert.x 5: @MailConnectionOptions for SMTP server configuration, MailService injection for sending text/HTML/multipart emails with attachments, connection pooling, StartTLS/SSL support, DKIM signing, environment variable overrides, and graceful shutdown. Use when sending emails via SMTP, configuring mail connections, or injecting mail services.
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
SKILL.md Source
# GuicedEE Mail Client
Annotation-driven SMTP mail client for GuicedEE using the Vert.x Mail Client.
## Core Concept
Declare SMTP connections with annotations — everything is discovered at startup via ClassGraph, wired through Guice, and managed by the Vert.x Mail Client with connection pooling.
## Required Flow
1. Add `com.guicedee:mail-client` dependency.
2. Define a connection on `package-info.java` (preferred) or any class:
```java
@MailConnectionOptions(
value = "notifications",
hostname = "smtp.example.com",
port = 587,
startTls = MailConnectionOptions.StartTLSMode.REQUIRED,
login = MailConnectionOptions.LoginMode.REQUIRED,
username = "user@example.com",
password = "secret",
defaultFrom = "noreply@example.com"
)
package com.example.mail;
```
3. Inject and send:
```java
public class NotificationService {
@Inject @Named("notifications")
private MailService mailService;
public void sendWelcome(String to) {
mailService.sendHtml(to, "Welcome!", "<h1>Welcome aboard!</h1>");
}
}
```
4. Or use full MailMessage for attachments:
```java
MailMessage message = new MailMessage()
.setTo("user@example.com")
.setSubject("Report")
.setText("See attached.")
.setAttachment(List.of(
MailAttachment.create()
.setContentType("application/pdf")
.setName("report.pdf")
.setData(Buffer.buffer(pdfBytes))
));
mailService.send(message);
```
5. Configure `module-info.java`:
```java
module my.app {
requires com.guicedee.mailclient;
opens my.app.mail to com.google.guice, com.guicedee.mailclient;
}
```
## Annotations
### `@MailConnectionOptions`
SMTP connection configuration: hostname, port, StartTLS, SSL, login credentials, connection pooling, DKIM, keep-alive, default from address. Targets `TYPE` and `PACKAGE`.
## Injectable Components
| Binding | Key | Description |
|---|---|---|
| `MailService` | `@Named("connection-name")` | High-level mail service with convenience send methods |
| `MailClient` | `@Named("connection-name")` | Raw Vert.x mail client per connection |
## Environment Variable Overrides
Every annotation attribute can be overridden via system properties or environment variables at runtime, scoped by connection name:
- `MAIL_{NORMALIZED_NAME}_{PROPERTY}` — name-specific override
- `MAIL_{PROPERTY}` — global fallback
Examples:
- `MAIL_NOTIFICATIONS_HOSTNAME=smtp.prod.example.com`
- `MAIL_NOTIFICATIONS_USERNAME=prod-user`
- `MAIL_NOTIFICATIONS_PASSWORD=prod-secret`
- `MAIL_PORT=465` (global fallback)
## Startup Flow
```
IGuiceContext.instance().inject()
└─ MailClientPreStartup (annotation scanning)
├─ Discovers @MailConnectionOptions (classes and package-info.java)
└─ Wraps with environment variable resolution
└─ MailClientModule (Guice bindings)
├─ Creates shared MailClient per connection (pooled)
├─ Binds MailClient as @Named("connection-name")
└─ Binds MailService as @Named("connection-name") singleton
└─ MailClientPostStartup (initialization logging)
└─ MailClientPreDestroy (shutdown)
└─ Closes all mail clients
```
## MailService Methods
| Method | Description |
|---|---|
| `send(MailMessage)` | Send a pre-built message (auto-fills from if defaultFrom set) |
| `sendText(to, subject, text)` | Send plain text using default from |
| `sendText(from, to, subject, text)` | Send plain text with explicit from |
| `sendHtml(to, subject, html)` | Send HTML using default from |
| `sendHtml(from, to, subject, html)` | Send HTML with explicit from |
| `sendMultipart(from, to, subject, text, html)` | Send multipart (text + HTML) |
| `getMailClient()` | Access underlying Vert.x MailClient |
## Non-Negotiable Constraints
- Module must `requires com.guicedee.mailclient;`.
- Packages using injection must `opens` to `com.google.guice` and `com.guicedee.mailclient`.
- `@MailConnectionOptions` can be placed on `package-info.java` (preferred) or any class.
- SPI implementations must be dual-registered (`module-info.java` + `META-INF/services/`).Related Skills
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