fix(mail): add base smtp config for mail sender

- Configure a default SMTP host and username so the JavaMailSender bean is always created
- Move from-address injection from a field to a setter

src/main/java/com/onixbyte/deltaforceguide/client/EmailClient.java

@@ -26,9 +26,6 @@ public class EmailClient {
 
     private final TemplateEngine emailTemplateEngine;
 
-    @Value("${spring.mail.username}")
-    private String fromAddress;
-
     @Autowired
     public EmailClient(
             JavaMailSender mailSender,
@@ -38,6 +35,13 @@ public class EmailClient {
         this.emailTemplateEngine = emailTemplateEngine;
     }
 
+    private String fromAddress;
+
+    @Autowired
+    public void setFromAddress(@Value("${spring.mail.username}") String fromAddress) {
+        this.fromAddress = fromAddress;
+    }
+
     /**
      * Send a template-based HTML email asynchronously.
      *

src/main/resources/application.yaml

@@ -32,6 +32,10 @@ spring:
     baseline-on-migrate: true
   thymeleaf:
     enabled: false
+  mail:
+    # This configuration is used to suppressing warnings of no beans found of JavaMailSender.
+    host: example.smtp.com
+    username: app@dfguide.onixbyte.cn
 
 mybatis:
   configuration: