diff --git a/packages/connector-smtp/README.md b/packages/connector-smtp/README.md
index 847e11262..acf5183e8 100644
--- a/packages/connector-smtp/README.md
+++ b/packages/connector-smtp/README.md
@@ -1,2 +1,126 @@
-### SMTP README
-placeholder
+# SMTP connector
+
+The SMTP (Simple Mail Transfer Protocol) is an internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive messages.
+
+## Set up SMTP connector
+
+SMTP is a transmission protocol that is not exclusive to some specific email service providers but can work with all providers.
+
+We are now offering guides on how to use the SMTP connector to send emails following providers for your better understanding:
+- _Gmail_ is the most popular email service vendor worldwide.
+- _Aliyun direct mail_ and _SendGrid mail_. Some of you might be familiar with these two email service providers because Logto Team provided corresponding connectors; you will likely have a general idea of them.
+
+We hope you can figure out all other email vendors' setups with the following examples :rocket:
+
+### Set up for Gmail use
+
+You can get a new Gmail account at [Gmail](https://mail.google.com/), or you can use an existing account if you have one.
+
+A [Gmail official post](https://support.google.com/a/answer/176600) shows how to determine required properties' values to operate Gmail via an SMTP connector.
+
+By following the post, your connector JSON should be like this:
+
+```json
+{
+    "host": "smtp.gmail.com",
+    "port": <port-number>,
+    "username": "<your-gmail-address>",
+    "password": "<password-to-previous-gmail-address>",
+    "fromEmail": "<your-gmail-address>",
+    "templates": [
+        {
+            "subject": "<register-template-subject>",
+            "content": "<Logto: Your passcode is {{code}}. (regitser template)>",
+            "usageType": "Register",
+            "contentType": "text/plain"
+        }
+    ]
+}
+```
+
+### Integrate with SendGrid SMTP API
+
+Initially, we assume that you already have a SendGrid account. If not, create a new account at the [SendGrid website](https://app.sendgrid.com/).
+
+You can find a step-by-step guide on [Integrating with the SMTP API](https://docs.sendgrid.com/for-developers/sending-email/integrating-with-the-smtp-api).
+
+Developers can access _Verified senders' details_ on the [_Sender Management_ page](https://mc.sendgrid.com/senders).
+
+After going through the guide, your connector JSON should look like this:
+
+```json
+{
+    "host": "smtp.sendgrid.net",
+    "port": 587,
+    "username": "apiKey",
+    "password": "<api-key-with-at-least-mail-permission>",
+    "fromEmail": "<email-address-of-a-verified-sender>",
+    "templates": [
+        {
+            "subject": "<register-template-subject>",
+            "content": "<Logto: Your passcode is {{code}}. (regitser template)>",
+            "usageType": "Register",
+            "contentType": "text/plain"
+        }
+    ]
+}
+```
+
+### Configure with Aliyun direct mail account
+
+Sign in to the [Aliyun website](https://cn.aliyun.com/). Register a new account if you don't have one.
+
+Follow the [Send emails using SMTP guide](https://www.alibabacloud.com/help/en/directmail/latest/send-emails-using-smtp) and finish those 'tasks' to get those required settings and information.
+
+You can go to [SMTP service address page](https://www.alibabacloud.com/help/en/directmail/latest/smtp-service-address) to choose a proper SMTP service address host and port number.
+
+To check _Sender Addresses_, you can find the entrance on the left-side navigation pane on [DirectMail console](https://dm.console.aliyun.com/). You should see `Sender address` and `SMTP Password` here.
+
+After going through the guide, your connector JSON should look like this:
+
+```json
+{
+    "host": "<SMTP-service-address>",
+    "port": <port-number>,
+    "username": "<email-address-of-chosen-sender-address>",
+    "password": "<api-key-with-at-least-mail-permission>",
+    "fromEmail": "<email-address-of-a-verified-sender-should-be-the-same-as-`username`>",
+    "templates": [
+        {
+            "subject": "<register-template-subject>",
+            "content": "<Logto: Your passcode is {{code}}. (regitser template)>",
+            "usageType": "Register",
+            "contentType": "text/plain"
+        }
+    ]
+}
+```
+
+> **Note**
+> Only one sample template is provided in the previous cases to keep things simple. You should add more templates for other use cases.
+> You should change values wrapped with "<" and ">" according to your SendGrid or Aliyun account settings and choose to keep other fields w/o "<" and ">".
+
+#### Config types
+
+| Name      | Type       |
+|-----------|------------|
+| host      | string     |
+| port      | string     |
+| username  | string     |
+| password  | string     |
+| fromEmail | string     |
+| templates | Template[] |
+
+| Template Properties | Type        | Enum values                      |
+|---------------------|-------------|----------------------------------|
+| subject             | string      | N/A                              |
+| content             | string      | N/A                              |
+| usageType           | enum string | 'Register' \| 'SignIn' \| 'Test' |
+| contentType         | enum string | 'text/plain' \| 'text/html'      |
+
+## References
+
+- [Gmail - Send email from a printer, scanner, or app](https://support.google.com/a/answer/176600)
+- [SendGrid - Integrating with the SMTP API](https://docs.sendgrid.com/for-developers/sending-email/integrating-with-the-smtp-api)
+- [Aliyun Direct Mail - Send emails using SMTP](https://www.alibabacloud.com/help/en/directmail/latest/send-emails-using-smtp)
+- [Aliyun Direct Mail - SMTP Reference](https://www.alibabacloud.com/help/en/directmail/latest/smtp-reference)