Add smtp output binding (#1166)

daprdocs/content/en/operations/components/setup-bindings/supported-bindings/_index.md

@@ -24,6 +24,7 @@ Every binding has its own unique set of properties. Click the name link to see t
 | [Postmark]({{< ref postmark.md >}})       |    | ✅ | Alpha |
 | [RabbitMQ]({{< ref rabbitmq.md >}})   | ✅ | ✅ | Alpha |
 | [Redis]({{< ref redis.md >}})         |    | ✅ | Alpha |
+| [SMTP]({{< ref smtp.md >}})         |    | ✅ | Alpha |
 | [Twilio]({{< ref twilio.md >}})       |    | ✅ | Alpha |
 | [Twitter]({{< ref twitter.md >}})       | ✅ | ✅ | Alpha |
 | [SendGrid]({{< ref sendgrid.md >}})       |    | ✅ | Alpha |

daprdocs/content/en/operations/components/setup-bindings/supported-bindings/smtp.md

@@ -0,0 +1,98 @@
+---
+type: docs
+title: "SMTP binding spec"
+linkTitle: "SMTP"
+description: "Detailed documentation on the SMTP binding component"
+---
+
+## Setup Dapr component
+
+```yaml
+apiVersion: dapr.io/v1alpha1
+kind: Component
+metadata:
+  name: smtp
+  namespace: default
+spec:
+  type: bindings.smtp
+  version: v1
+  metadata:
+  - name: host
+    value: "smtp host" 
+  - name: port
+    value: "smtp port"
+  - name: user
+    value: "username"
+  - name: password
+    value: "password"
+  - name: skipTLSVerify
+    value: true|false
+  - name: emailFrom
+    value: "sender@example.com"
+  - name: emailTo
+    value: "receiver@example.com"
+  - name: emailCC
+    value: "cc@example.com"
+  - name: emailBCC
+    value: "bcc@example.com"
+  - name: subject
+    value: "subject"
+```
+
+{{% alert title="Warning" color="warning" %}}
+The example configuration shown above, contain a username and password as plain-text strings. It is recommended to use a secret store for the secrets as described [here]({{< ref component-secrets.md >}}).
+{{% /alert %}}
+
+- `host` The host where your SMTP server runs. Required.
+- `port` The port your SMTP server listens on. Required.
+- `user` The user to authenticate against the SMTP server. Required.
+- `password` The password of the user. Required.
+- `skipTLSVerify` If set to true, the SMPT server's TLS certificate will not be verified. Optional field.
+- `emailFrom` If set, this specifies the email address of the sender. Optional field, see below.
+- `emailTo` If set, this specifies the email address of the receiver. Optional field, see below.
+- `emailCc` If set, this specifies the email address to CC in. Optional field, see below.
+- `emailBcc` If set, this specifies email address to BCC in. Optional field, see below.
+- `subject` If set, this specifies the subject of the email message. Optional field, see below.
+
+{{% alert title="Warning" color="warning" %}}
+Skipping TLS certificate verification by setting `skipTLSVerify` to `true`, is only allowed for development- or test-activities and not suitable in production scenarios.
+{{% /alert %}}
+
+You can specify any of the following optional metadata properties with each request:
+
+- `emailFrom`
+- `emailTo`
+- `emailCC`
+- `emailBCC`
+- `subject`
+
+When sending an email, the metadata in the configuration and in the request is combined. The combined set of metadata must contain at least the `emailFrom`, `emailTo` and `subject` fields.
+
+The `emailTo`, `emailCC` and `emailBCC` fields can contain multiple email addresses separated by a semicolon.
+
+Example request payload:
+
+```json
+{
+  "operation": "create",
+  "metadata": {
+    "emailTo": "dapr-smtp-binding@example.net",
+    "emailCC": "cc1@example.net; cc2@example.net",
+    "subject": "Email subject"
+  },
+  "data": "Testing Dapr SMTP Binding"
+}
+```
+
+The `emailTo`, `emailCC` and `emailBCC` fields can contain multiple email addresses separated by a semicolon.
+
+## Output Binding Supported Operations
+
+- `create`
+
+## Related links
+
+- [Bindings building block]({{< ref bindings >}})
+- [How-To: Trigger application with input binding]({{< ref howto-triggers.md >}})
+- [How-To: Use bindings to interface with external resources]({{< ref howto-bindings.md >}})
+- [Bindings API reference]({{< ref bindings_api.md >}})