commit 70d1d6bce8e7331724dd480782fc74607160afc3
Author: Oliver Jakoubek <mail@oliverjakoubek.de>
Date:   Tue Nov 18 17:54:34 2025 +0100

    Initial release

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.idea/
+.vscode/
\ No newline at end of file
diff --git a/LICENSE b/LICENSE
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index 0000000..df28f57
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 Oliver Jakoubek, Beautiful Machines
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,225 @@
+# Sendamatic Go Client
+
+A Go client library for the [Sendamatic](https://www.sendamatic.net) email delivery API.
+
+## Features
+
+- Simple and idiomatic Go API
+- Context support for timeouts and cancellation
+- Fluent message builder interface
+- Support for HTML and plain text emails
+- File attachments with automatic base64 encoding
+- Custom headers
+- Multiple recipients (To, CC, BCC)
+- Comprehensive error handling
+
+## Installation
+```bash
+go get code.beautifulmachines.dev/jakoubek/sendamatic
+```
+
+## Quick Start
+```go
+package main
+
+import (
+    "context"
+    "log"
+
+    "code.beautifulmachines.dev/jakoubek/sendamatic"
+)
+
+func main() {
+    // Create client
+    client := sendamatic.NewClient("your-user-id", "your-password")
+
+    // Build message
+    msg := sendamatic.NewMessage().
+        SetSender("sender@example.com").
+        AddTo("recipient@example.com").
+        SetSubject("Hello from Sendamatic").
+        SetTextBody("This is a test message.").
+        SetHTMLBody("<h1>Hello!</h1><p>This is a test message.</p>")
+
+    // Send email
+    resp, err := client.Send(context.Background(), msg)
+    if err != nil {
+        log.Fatal(err)
+    }
+
+    log.Printf("Email sent successfully: %d", resp.StatusCode)
+}
+```
+
+## Usage Examples
+
+### Basic Email
+```go
+msg := sendamatic.NewMessage().
+    SetSender("sender@example.com").
+    AddTo("recipient@example.com").
+    SetSubject("Hello World").
+    SetTextBody("This is a plain text email.")
+
+resp, err := client.Send(context.Background(), msg)
+```
+
+### HTML Email with Multiple Recipients
+```go
+msg := sendamatic.NewMessage().
+    SetSender("newsletter@example.com").
+    AddTo("user1@example.com").
+    AddTo("user2@example.com").
+    AddCC("manager@example.com").
+    AddBCC("archive@example.com").
+    SetSubject("Monthly Newsletter").
+    SetHTMLBody("<h1>Newsletter</h1><p>Your monthly update...</p>").
+    SetTextBody("Newsletter - Your monthly update...")
+```
+
+### Email with Attachments
+```go
+// From file path
+msg := sendamatic.NewMessage().
+    SetSender("sender@example.com").
+    AddTo("recipient@example.com").
+    SetSubject("Invoice").
+    SetTextBody("Please find your invoice attached.")
+
+err := msg.AttachFileFromPath("./invoice.pdf", "application/pdf")
+if err != nil {
+    log.Fatal(err)
+}
+
+// Or from byte slice
+pdfData := []byte{...}
+msg.AttachFile("invoice.pdf", "application/pdf", pdfData)
+```
+
+### Custom Headers
+```go
+msg := sendamatic.NewMessage().
+    SetSender("sender@example.com").
+    AddTo("recipient@example.com").
+    SetSubject("Custom Headers").
+    SetTextBody("Email with custom headers").
+    AddHeader("Reply-To", "support@example.com").
+    AddHeader("X-Priority", "1")
+```
+
+### With Timeout
+```go
+client := sendamatic.NewClient(
+    "user-id",
+    "password",
+    sendamatic.WithTimeout(45*time.Second),
+)
+
+ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+defer cancel()
+
+resp, err := client.Send(ctx, msg)
+```
+
+### Custom HTTP Client
+```go
+httpClient := &http.Client{
+    Timeout: 60 * time.Second,
+    Transport: &http.Transport{
+        MaxIdleConns: 10,
+    },
+}
+
+client := sendamatic.NewClient(
+    "user-id",
+    "password",
+    sendamatic.WithHTTPClient(httpClient),
+)
+```
+
+## Configuration Options
+
+The client supports various configuration options via the functional options pattern:
+```go
+client := sendamatic.NewClient(
+    "user-id",
+    "password",
+    sendamatic.WithBaseURL("https://custom.api.url"),
+    sendamatic.WithTimeout(60*time.Second),
+    sendamatic.WithHTTPClient(customHTTPClient),
+)
+```
+
+## Response Handling
+
+The `SendResponse` provides methods to check the delivery status:
+```go
+resp, err := client.Send(ctx, msg)
+if err != nil {
+    log.Fatal(err)
+}
+
+// Check overall success
+if resp.IsSuccess() {
+    log.Println("Email sent successfully")
+}
+
+// Check individual recipient status
+for email := range resp.Recipients {
+    if status, ok := resp.GetStatus(email); ok {
+        log.Printf("Recipient %s: status %d", email, status)
+    }
+    if msgID, ok := resp.GetMessageID(email); ok {
+        log.Printf("Message ID: %s", msgID)
+    }
+}
+```
+
+## Error Handling
+
+The library provides typed errors for better error handling:
+```go
+resp, err := client.Send(ctx, msg)
+if err != nil {
+    var apiErr *sendamatic.APIError
+    if errors.As(err, &apiErr) {
+        log.Printf("API error (status %d): %s", apiErr.StatusCode, apiErr.Message)
+        if apiErr.ValidationErrors != "" {
+            log.Printf("Validation: %s", apiErr.ValidationErrors)
+        }
+    } else {
+        log.Printf("Other error: %v", err)
+    }
+}
+```
+
+## Requirements
+
+- Go 1.22 or higher
+- Valid Sendamatic account with API credentials
+
+## API Credentials
+
+Your API credentials consist of:
+- **User ID**: Your Mail Credential User ID
+- **Password**: Your Mail Credential Password
+
+Find these in your Sendamatic dashboard under Mail Credentials.
+
+## Documentation
+
+For detailed API documentation, visit:
+- [Sendamatic API Documentation](https://docs.sendamatic.net/api/send/)
+- [Sendamatic Website](https://www.sendamatic.net)
+
+## License
+
+MIT License - see [LICENSE](LICENSE) file for details.
+
+## Contributing
+
+Contributions are welcome! Please feel free to submit issues or pull requests.
+
+## Author
+
+Oliver Jakoubek ([info@jakoubek.net](mailto:info@jakoubek.net))
\ No newline at end of file
diff --git a/client.go b/client.go
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--- /dev/null
+++ b/client.go
@@ -0,0 +1,83 @@
+package sendamatic
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+const (
+	defaultBaseURL = "https://send.api.sendamatic.net"
+	defaultTimeout = 30 * time.Second
+)
+
+type Client struct {
+	apiKey     string
+	baseURL    string
+	httpClient *http.Client
+}
+
+func NewClient(userID, password string, opts ...Option) *Client {
+	c := &Client{
+		apiKey:  fmt.Sprintf("%s-%s", userID, password),
+		baseURL: defaultBaseURL,
+		httpClient: &http.Client{
+			Timeout: defaultTimeout,
+		},
+	}
+
+	// Optionen anwenden
+	for _, opt := range opts {
+		opt(c)
+	}
+
+	return c
+}
+
+// Send versendet eine E-Mail über die Sendamatic API
+func (c *Client) Send(ctx context.Context, msg *Message) (*SendResponse, error) {
+	if err := msg.Validate(); err != nil {
+		return nil, fmt.Errorf("message validation failed: %w", err)
+	}
+
+	payload, err := json.Marshal(msg)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal message: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/send", bytes.NewReader(payload))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("x-api-key", c.apiKey)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+
+	// Fehlerbehandlung für 4xx und 5xx
+	if resp.StatusCode >= 400 {
+		return nil, parseErrorResponse(resp.StatusCode, body)
+	}
+
+	var sendResp SendResponse
+	if err := json.Unmarshal(body, &sendResp.Recipients); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal response: %w", err)
+	}
+
+	sendResp.StatusCode = resp.StatusCode
+	return &sendResp, nil
+}
diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..9d3e22a
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,36 @@
+package sendamatic
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// APIError repräsentiert einen API-Fehler
+type APIError struct {
+	StatusCode       int    `json:"-"`
+	Message          string `json:"error"`
+	ValidationErrors string `json:"validation_errors,omitempty"`
+	JSONPath         string `json:"json_path,omitempty"`
+	Sender           string `json:"sender,omitempty"`
+	SMTPCode         int    `json:"smtp_code,omitempty"`
+}
+
+func (e *APIError) Error() string {
+	if e.ValidationErrors != "" {
+		return fmt.Sprintf("sendamatic api error (status %d): %s (path: %s)",
+			e.StatusCode, e.ValidationErrors, e.JSONPath)
+	}
+	return fmt.Sprintf("sendamatic api error (status %d): %s", e.StatusCode, e.Message)
+}
+
+func parseErrorResponse(statusCode int, body []byte) error {
+	var apiErr APIError
+	apiErr.StatusCode = statusCode
+
+	if err := json.Unmarshal(body, &apiErr); err != nil {
+		// Fallback, falls JSON nicht parsebar ist
+		apiErr.Message = string(body)
+	}
+
+	return &apiErr
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..bf8c1e1
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module code.beautifulmachines.dev/jakoubek/sendamatic
+
+go 1.25.4
diff --git a/message.go b/message.go
new file mode 100644
index 0000000..279a877
--- /dev/null
+++ b/message.go
@@ -0,0 +1,147 @@
+package sendamatic
+
+import (
+	"encoding/base64"
+	"errors"
+	"os"
+)
+
+// Message repräsentiert eine E-Mail-Nachricht
+type Message struct {
+	To          []string     `json:"to"`
+	CC          []string     `json:"cc,omitempty"`
+	BCC         []string     `json:"bcc,omitempty"`
+	Sender      string       `json:"sender"`
+	Subject     string       `json:"subject"`
+	TextBody    string       `json:"text_body,omitempty"`
+	HTMLBody    string       `json:"html_body,omitempty"`
+	Headers     []Header     `json:"headers,omitempty"`
+	Attachments []Attachment `json:"attachments,omitempty"`
+}
+
+// Header repräsentiert einen benutzerdefinierten E-Mail-Header
+type Header struct {
+	Header string `json:"header"`
+	Value  string `json:"value"`
+}
+
+// Attachment repräsentiert einen E-Mail-Anhang
+type Attachment struct {
+	Filename string `json:"filename"`
+	Data     string `json:"data"` // Base64-kodiert
+	MimeType string `json:"mimetype"`
+}
+
+// NewMessage erstellt eine neue Message
+func NewMessage() *Message {
+	return &Message{
+		To:          []string{},
+		CC:          []string{},
+		BCC:         []string{},
+		Headers:     []Header{},
+		Attachments: []Attachment{},
+	}
+}
+
+// AddTo fügt einen Empfänger hinzu
+func (m *Message) AddTo(email string) *Message {
+	m.To = append(m.To, email)
+	return m
+}
+
+// AddCC fügt einen CC-Empfänger hinzu
+func (m *Message) AddCC(email string) *Message {
+	m.CC = append(m.CC, email)
+	return m
+}
+
+// AddBCC fügt einen BCC-Empfänger hinzu
+func (m *Message) AddBCC(email string) *Message {
+	m.BCC = append(m.BCC, email)
+	return m
+}
+
+// SetSender setzt den Absender
+func (m *Message) SetSender(email string) *Message {
+	m.Sender = email
+	return m
+}
+
+// SetSubject setzt den Betreff
+func (m *Message) SetSubject(subject string) *Message {
+	m.Subject = subject
+	return m
+}
+
+// SetTextBody setzt den Text-Körper
+func (m *Message) SetTextBody(body string) *Message {
+	m.TextBody = body
+	return m
+}
+
+// SetHTMLBody setzt den HTML-Körper
+func (m *Message) SetHTMLBody(body string) *Message {
+	m.HTMLBody = body
+	return m
+}
+
+// AddHeader fügt einen benutzerdefinierten Header hinzu
+func (m *Message) AddHeader(name, value string) *Message {
+	m.Headers = append(m.Headers, Header{
+		Header: name,
+		Value:  value,
+	})
+	return m
+}
+
+// AttachFile fügt eine Datei als Anhang hinzu
+func (m *Message) AttachFile(filename, mimeType string, data []byte) *Message {
+	m.Attachments = append(m.Attachments, Attachment{
+		Filename: filename,
+		Data:     base64.StdEncoding.EncodeToString(data),
+		MimeType: mimeType,
+	})
+	return m
+}
+
+// AttachFileFromPath lädt eine Datei vom Dateisystem und fügt sie als Anhang hinzu
+func (m *Message) AttachFileFromPath(path, mimeType string) error {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	// Extrahiere Dateinamen aus Pfad
+	filename := path
+	if idx := len(path) - 1; idx >= 0 {
+		for i := idx; i >= 0; i-- {
+			if path[i] == '/' || path[i] == '\\' {
+				filename = path[i+1:]
+				break
+			}
+		}
+	}
+
+	m.AttachFile(filename, mimeType, data)
+	return nil
+}
+
+// Validate prüft, ob die Message gültig ist
+func (m *Message) Validate() error {
+	if len(m.To) == 0 {
+		return errors.New("at least one recipient required")
+	}
+	if len(m.To) > 255 {
+		return errors.New("maximum 255 recipients allowed")
+	}
+	if m.Sender == "" {
+		return errors.New("sender is required")
+	}
+	if m.Subject == "" {
+		return errors.New("subject is required")
+	}
+	if m.TextBody == "" && m.HTMLBody == "" {
+		return errors.New("either text_body or html_body is required")
+	}
+	return nil
+}
diff --git a/options.go b/options.go
new file mode 100644
index 0000000..322aad9
--- /dev/null
+++ b/options.go
@@ -0,0 +1,26 @@
+package sendamatic
+
+import (
+	"net/http"
+	"time"
+)
+
+type Option func(*Client)
+
+func WithBaseURL(baseURL string) Option {
+	return func(c *Client) {
+		c.baseURL = baseURL
+	}
+}
+
+func WithHTTPClient(client *http.Client) Option {
+	return func(c *Client) {
+		c.httpClient = client
+	}
+}
+
+func WithTimeout(timeout time.Duration) Option {
+	return func(c *Client) {
+		c.httpClient.Timeout = timeout
+	}
+}
diff --git a/response.go b/response.go
new file mode 100644
index 0000000..40af7d8
--- /dev/null
+++ b/response.go
@@ -0,0 +1,33 @@
+package sendamatic
+
+// SendResponse repräsentiert die Antwort auf einen Send-Request
+type SendResponse struct {
+	StatusCode int
+	Recipients map[string][2]interface{} // Email -> [StatusCode, MessageID]
+}
+
+// IsSuccess prüft, ob die gesamte Sendung erfolgreich war
+func (r *SendResponse) IsSuccess() bool {
+	return r.StatusCode == 200
+}
+
+// GetMessageID gibt die Message-ID für einen Empfänger zurück
+func (r *SendResponse) GetMessageID(email string) (string, bool) {
+	if info, ok := r.Recipients[email]; ok && len(info) >= 2 {
+		if msgID, ok := info[1].(string); ok {
+			return msgID, true
+		}
+	}
+	return "", false
+}
+
+// GetStatus gibt den Status-Code für einen Empfänger zurück
+func (r *SendResponse) GetStatus(email string) (int, bool) {
+	if info, ok := r.Recipients[email]; ok && len(info) >= 1 {
+		// Die API gibt float64 zurück, da JSON numbers als float64 dekodiert werden
+		if status, ok := info[0].(float64); ok {
+			return int(status), true
+		}
+	}
+	return 0, false
+}