improve sso callback path (#6676)

* normalize base_url for sso_callback_path

* clean url when embedding images

src/config.rs

@@ -1325,12 +1325,16 @@ fn generate_smtp_img_src(embed_images: bool, domain: &str) -> String {
     if embed_images {
         "cid:".to_string()
     } else {
-        format!("{domain}/vw_static/")
+        // normalize base_url
+        let base_url = domain.trim_end_matches('/');
+        format!("{base_url}/vw_static/")
     }
 }
 
 fn generate_sso_callback_path(domain: &str) -> String {
-    format!("{domain}/identity/connect/oidc-signin")
+    // normalize base_url
+    let base_url = domain.trim_end_matches('/');
+    format!("{base_url}/identity/connect/oidc-signin")
 }
 
 /// Generate the correct URL for the icon service.