feat: add docs for reply to

docs/mail/configuration.md

@@ -17,7 +17,7 @@ next:
 
 To configure mail, create a `config/mail.js` configuration file. Let's look at all the possible configurations you can have in `config/mail.js`
 
-## default
+## `default`
 
 The `default` config in `config/mail.js` tells Mail which mailer to use by default. The string passed to `default` must be the name of a registered mailer in the `mailers` object
 
@@ -40,7 +40,7 @@ mail: {
 }
 ```
 
-## mailers
+## `mailers`
 
 The `mailers` configuration object contains
 
@@ -63,9 +63,9 @@ The `mailers` configuration object contains
 In Mail, a mailer is a configuration object that is registered in the `mailers` object in `config/mails.js` or in a `mail` object in `local.js` that specifies at the very least a transport that Mail will use in sending your emails.
 :::
 
-## from
+## `from`
 
-This config let you set a global from address for all your emails. It's really useful if your application sends emails from the same from address.
+This config lets you set a global from address for all your emails. It's really useful if your application sends emails from the same from address.
 
 By default Mail will use this address if no address is passed when you send an email with `sails.helpers.mail.send`
 
@@ -77,3 +77,15 @@ from: {
 ```
 
 You can also set this config by specifying these two environment variables: `MAIL_FROM_NAME` and `MAIL_FROM_ADDRESS`.
+
+## `replyTo`
+
+This config lets you set a global reply-to address for all your emails. It's useful if you want replies to go to a specific address.
+
+Mail will use this address by default if no `replyTo` address is provided when sending an email with `sails.helpers.mail.send`.
+
+```js
+replyTo: 'reply@sailscasts.com'
+```
+
+You can also set this config by specifying the environment variable `MAIL_REPLY_TO`.