From a3cdc094e8fba1083f9887220de20a8a4ffdda3f Mon Sep 17 00:00:00 2001
From: rustmailer <pollybase@zohomail.com>
Date: Thu, 21 May 2026 23:32:42 +0800
Subject: [PATCH] feat:  Strip remote data from emails when viewed #54

---
 Cargo.lock                                    |  16 +-
 Cargo.toml                                    |   6 +-
 crates/core/src/message/content.rs            |  27 +++
 crates/core/src/utils/html.rs                 | 182 ++++++++++++++++++
 crates/server/src/rest/api/message.rs         |  14 +-
 web/src/api/mailbox/envelope/api.ts           |  24 ++-
 web/src/components/mail-iframe.tsx            |   2 +-
 .../features/attachment/mail-message-view.tsx |  41 +++-
 .../attachment/nested-email-dialog.tsx        |   2 +-
 web/src/features/search/mail-message-view.tsx |  41 +++-
 .../features/search/nested-email-dialog.tsx   |   2 +-
 11 files changed, 331 insertions(+), 26 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index bd13052..a34b720 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1006,9 +1006,9 @@ dependencies = [
 
 [[package]]
 name = "dashmap"
-version = "6.1.0"
+version = "6.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5041cc499144891f3790297212f32a74fb938e5136a14943f338ef9e0ae276cf"
+checksum = "e6361d5c062261c78a176addb82d4c821ae42bed6089de0e12603cd25de2059c"
 dependencies = [
  "cfg-if",
  "crossbeam-utils",
@@ -2254,9 +2254,9 @@ checksum = "52ff2c0fe9bc6cb6b14a0592c2ff4fa9ceb83eea9db979b0487cd054946a2b8f"
 
 [[package]]
 name = "libmimalloc-sys"
-version = "0.1.47"
+version = "0.1.48"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2d1eacfa31c33ec25e873c136ba5669f00f9866d0688bea7be4d3f7e43067df6"
+checksum = "2892ae4ea6fa2cb7acb0e236a6880d39523239cd9089de71d220910ccc806790"
 dependencies = [
  "cc",
 ]
@@ -2467,9 +2467,9 @@ dependencies = [
 
 [[package]]
 name = "mimalloc"
-version = "0.1.50"
+version = "0.1.51"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b3627c4272df786b9260cabaa46aec1d59c93ede723d4c3ef646c503816b0640"
+checksum = "ebca48a43116bc25f18a61360f1be98412f50cc218f5e52c823086b999a4a21a"
 dependencies = [
  "libmimalloc-sys",
 ]
@@ -4286,9 +4286,9 @@ dependencies = [
 
 [[package]]
 name = "sysinfo"
-version = "0.39.1"
+version = "0.39.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a4deba334e1190ba7cb498327affa11e5ece10d26a30ab2f27fcf09504b8d8b6"
+checksum = "14311e7e9a03114cd4b65eedd54e8fed2945e17f08586ae97ef53bc0669f9581"
 dependencies = [
  "libc",
  "memchr",
diff --git a/Cargo.toml b/Cargo.toml
index 1819a8b..ee56a03 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ edition = "2021"
 [workspace.dependencies]
 chrono = "0.4.44"
 clap = { version = "4.6.1", features = ["derive", "env"] }
-mimalloc = "0.1.50"
+mimalloc = "0.1.51"
 memdb = { path = "crates/memdb" }
 itertools = "0.14.0"
 ring = { version = "0.17.14", features = ["std"] }
@@ -52,7 +52,7 @@ tokio-rustls = { version = "0.26.4", default-features = false, features = [
 timeago = "0.6.0"
 oauth2 = { version = "5.0.0", features = ["reqwest-blocking"] }
 url = { version = "2.5.8", features = ["serde"] }
-sysinfo = "0.39.1"
+sysinfo = "0.39.2"
 num_cpus = "1.17.0"
 rand = "0.10.1"
 encoding_rs = "0.8.35"
@@ -73,7 +73,7 @@ time = { version = "0.3.47", features = [
 rust-embed = "8.11.0"
 murmur3 = "0.5.2"
 urlencoding = "2.1.3"
-dashmap = "6.1.0"
+dashmap = "6.2.1"
 gethostname = "1.1.0"
 itoa = "1.0.18"
 html2text = "0.17.1"
diff --git a/crates/core/src/message/content.rs b/crates/core/src/message/content.rs
index 0451959..0f9fb4c 100644
--- a/crates/core/src/message/content.rs
+++ b/crates/core/src/message/content.rs
@@ -22,6 +22,7 @@ use crate::envelope::extractor::{extract_envelope_from_nested_message, reattach_
 use crate::error::code::ErrorCode;
 use crate::store::envelope::Envelope;
 use crate::utils::compute_content_hash;
+use crate::utils::html::block_remote_content;
 use crate::{error::BichonResult, raise_error};
 use mail_parser::{MessageParser, MimeHeaders};
 //use poem_openapi::Object;
@@ -142,6 +143,9 @@ pub struct FullMessageContent {
     pub html: Option<String>,
     // all Attachments include inline attachments
     pub attachments: Option<Vec<AttachmentInfo>>,
+    /// True when remote content (http/https URLs) was detected and stripped from html.
+    #[serde(default)]
+    pub has_remote_content: bool,
 }
 
 #[derive(Clone, Debug, Default, Eq, PartialEq, Deserialize, Serialize)]
@@ -155,11 +159,15 @@ pub struct FullNestedMessageContent {
     pub attachments: Option<Vec<AttachmentInfo>>,
     /// Metadata for the email envelope.
     pub envelope: Envelope,
+    /// True when remote content (http/https URLs) was detected and stripped from html.
+    #[serde(default)]
+    pub has_remote_content: bool,
 }
 
 pub fn retrieve_email_content(
     account_id: u64,
     envelope_id: String,
+    block_remote: bool,
 ) -> BichonResult<FullMessageContent> {
     AccountModel::check_account_exists(account_id)?;
     let (envelope, eml) = reattach_eml_content(account_id, envelope_id)?;
@@ -223,10 +231,19 @@ pub fn retrieve_email_content(
             content_id: attachment.content_id().map(Into::into),
         });
     }
+    let mut has_remote_content = false;
+    if let Some(ref html_body) = html {
+        let filtered = block_remote_content(html_body);
+        has_remote_content = *html_body != filtered;
+        if block_remote {
+            html = Some(filtered);
+        }
+    }
     Ok(FullMessageContent {
         text,
         html,
         attachments: Some(attachments),
+        has_remote_content,
     })
 }
 
@@ -234,6 +251,7 @@ pub fn retrieve_nested_eml_content(
     account_id: u64,
     envelope_id: String,
     content_hash: &str,
+    block_remote: bool,
 ) -> BichonResult<FullNestedMessageContent> {
     let (_, eml) = reattach_eml_content(account_id, envelope_id)?;
     let parent_message = MessageParser::default().parse(&eml).ok_or_else(|| {
@@ -314,10 +332,19 @@ pub fn retrieve_nested_eml_content(
 
     let envelope = extract_envelope_from_nested_message(nested_message, account_id)?;
 
+    let mut has_remote_content = false;
+    if let Some(ref html_body) = html {
+        let filtered = block_remote_content(html_body);
+        has_remote_content = *html_body != filtered;
+        if block_remote {
+            html = Some(filtered);
+        }
+    }
     Ok(FullNestedMessageContent {
         text,
         html,
         attachments: Some(attachments),
         envelope,
+        has_remote_content,
     })
 }
diff --git a/crates/core/src/utils/html.rs b/crates/core/src/utils/html.rs
index 6080dc4..029fea7 100644
--- a/crates/core/src/utils/html.rs
+++ b/crates/core/src/utils/html.rs
@@ -17,9 +17,63 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
+use regex::Regex;
 use std::panic;
+use std::sync::LazyLock;
 use tracing::error;
 
+/// Removes remote content references from HTML email body.
+///
+/// Strips attributes that load content from http:// or https:// URLs,
+/// keeping data: URIs and cid: references intact. Does NOT affect
+/// navigation links (<a href>).
+pub fn block_remote_content(html: &str) -> String {
+    let mut result = html.to_string();
+
+    // 1. Strip src, poster, data attributes with remote URLs.
+    //    These always load content regardless of the tag.
+    static SRC_ATTR_RE: LazyLock<Regex> = LazyLock::new(|| {
+        Regex::new(r#"(?i)\s+(src|poster|data)\s*=\s*["'][^"']*(?:https?://|//)[^"']*["']"#).unwrap()
+    });
+    result = SRC_ATTR_RE.replace_all(&result, "").to_string();
+
+    // 2. Strip srcset attributes with remote URLs.
+    static SRCSET_ATTR_RE: LazyLock<Regex> = LazyLock::new(|| {
+        Regex::new(r#"(?i)\s+srcset\s*=\s*["'][^"']*(?:https?://|//)[^"']*["']"#).unwrap()
+    });
+    result = SRCSET_ATTR_RE.replace_all(&result, "").to_string();
+
+    // 3. Strip href on <link> tags (stylesheets), never <a> links.
+    static LINK_HREF_RE: LazyLock<Regex> = LazyLock::new(|| {
+        Regex::new(r#"(?i)(<link\b[^>]*)\s+href\s*=\s*["'][^"']*(?:https?://|//)[^"']*["']"#).unwrap()
+    });
+    result = LINK_HREF_RE.replace_all(&result, "$1").to_string();
+
+    // 4. Strip CSS url() references with remote URLs in inline styles.
+    static CSS_URL_RE: LazyLock<Regex> = LazyLock::new(|| {
+        Regex::new(r#"(?i)url\(\s*["']?\s*(?:https?://|//)[^)"'\s]*\s*["']?\s*\)"#).unwrap()
+    });
+    result = CSS_URL_RE.replace_all(&result, "").to_string();
+
+    // 5. Strip @import url(...) with remote URLs inside <style> blocks.
+    static IMPORT_URL_RE: LazyLock<Regex> = LazyLock::new(|| {
+        Regex::new(
+            r#"(?i)@import\s+url\(\s*["']?\s*(?:https?://|//)[^)"'\s]*\s*["']?\s*\)\s*;"#,
+        )
+        .unwrap()
+    });
+    result = IMPORT_URL_RE.replace_all(&result, "").to_string();
+
+    // 6. Strip background attribute on <body> with remote URLs.
+    static BODY_BG_RE: LazyLock<Regex> = LazyLock::new(|| {
+        Regex::new(r#"(?i)(<body\b[^>]*)\s+background\s*=\s*["'][^"']*(?:https?://|//)[^"']*["']"#)
+            .unwrap()
+    });
+    result = BODY_BG_RE.replace_all(&result, "$1").to_string();
+
+    result
+}
+
 pub fn extract_text(html: String) -> String {
     let result = panic::catch_unwind(|| {
         html2text::config::plain()
@@ -88,4 +142,132 @@ mod tests {
         let text = extract_text(html);
         assert!(text.contains("Click here"));
     }
+
+    mod block_remote {
+        use super::*;
+
+        #[test]
+        fn strips_img_src_http() {
+            let html = r#"<img src="https://tracker.example.com/pixel.gif" alt="x">"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://tracker.example.com"));
+            assert!(result.contains("alt=")); // other attrs preserved
+        }
+
+        #[test]
+        fn strips_img_src_protocol_relative() {
+            let html = r#"<img src="//tracker.example.com/pixel.gif">"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("//tracker.example.com"));
+        }
+
+        #[test]
+        fn preserves_data_uri() {
+            let html = r#"<img src="data:image/png;base64,ABC123" alt="embedded">"#;
+            let result = block_remote_content(html);
+            assert!(result.contains("data:image/png;base64,ABC123"));
+        }
+
+        #[test]
+        fn preserves_cid_reference() {
+            let html = r#"<img src="cid:abc123@example.com" alt="inline">"#;
+            let result = block_remote_content(html);
+            assert!(result.contains("cid:abc123@example.com"));
+        }
+
+        #[test]
+        fn preserves_anchor_href() {
+            let html = r#"<a href="https://example.com/page">Click</a>"#;
+            let result = block_remote_content(html);
+            assert!(result.contains(r#"href="https://example.com/page""#));
+        }
+
+        #[test]
+        fn strips_link_stylesheet_href() {
+            let html =
+                r#"<link rel="stylesheet" href="https://fonts.example.com/font.css">"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://fonts.example.com"));
+            assert!(result.contains("<link")); // tag preserved
+        }
+
+        #[test]
+        fn strips_script_src() {
+            let html = r#"<script src="https://evil.example.com/malware.js"></script>"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://evil.example.com"));
+        }
+
+        #[test]
+        fn strips_iframe_src() {
+            let html = r#"<iframe src="https://ads.example.com/banner"></iframe>"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://ads.example.com"));
+        }
+
+        #[test]
+        fn strips_css_url_in_style() {
+            let html = r#"<div style="background: url(https://tracker.example.com/bg.jpg)"></div>"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://tracker.example.com"));
+        }
+
+        #[test]
+        fn strips_css_url_protocol_relative() {
+            let html = r#"<div style="background: url(//tracker.example.com/bg.jpg)"></div>"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("//tracker.example.com"));
+        }
+
+        #[test]
+        fn strips_css_import() {
+            let html =
+                r#"<style>@import url("https://fonts.example.com/font.css");</style>"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://fonts.example.com"));
+        }
+
+        #[test]
+        fn strips_video_poster() {
+            let html = r#"<video poster="https://cdn.example.com/thumb.jpg"></video>"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://cdn.example.com"));
+        }
+
+        #[test]
+        fn strips_srcset() {
+            let html =
+                r#"<img srcset="https://cdn.example.com/img1.jpg 1x, https://cdn.example.com/img2.jpg 2x">"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://cdn.example.com"));
+        }
+
+        #[test]
+        fn strips_body_background() {
+            let html = r#"<body background="https://tracker.example.com/bg.jpg">"#;
+            let result = block_remote_content(html);
+            assert!(!result.contains("https://tracker.example.com"));
+            assert!(result.contains("<body"));
+        }
+
+        #[test]
+        fn handles_mixed_content() {
+            let html = r#"
+            <html>
+              <body>
+                <img src="https://spy.example.com/pixel.gif" width="1" height="1">
+                <img src="data:image/png;base64,OK123" alt="ok">
+                <a href="https://example.com/read-more">Read more</a>
+                <div style="background: url(https://tracker.example.com/bg.jpg) no-repeat"></div>
+              </body>
+            </html>"#;
+            let result = block_remote_content(html);
+            // Remote content gone
+            assert!(!result.contains("spy.example.com"));
+            assert!(!result.contains("tracker.example.com"));
+            // Safe content preserved
+            assert!(result.contains("data:image/png;base64,OK123"));
+            assert!(result.contains(r#"href="https://example.com/read-more""#));
+        }
+    }
 }
diff --git a/crates/server/src/rest/api/message.rs b/crates/server/src/rest/api/message.rs
index f426625..3c995de 100644
--- a/crates/server/src/rest/api/message.rs
+++ b/crates/server/src/rest/api/message.rs
@@ -121,6 +121,8 @@ impl MessageApi {
     }
 
     /// Fetches the content of a specific email.
+    /// Set `block_remote_content=true` to strip external images, scripts,
+    /// and other content loaded from http/https URLs.
     #[oai(
         path = "/message-content/:account_id/:envelope_id",
         method = "get",
@@ -132,11 +134,18 @@ impl MessageApi {
         account_id: Path<u64>,
         /// The ID of the message to fetch.
         envelope_id: Path<String>,
+        /// Block remote content (http/https URLs) from email body.
+        block_remote_content: Query<Option<bool>>,
         context: WrappedContext,
     ) -> ApiResult<Json<FullMessageContent>> {
         let account_id = account_id.0;
+        let block_remote = block_remote_content.0.unwrap_or(false);
         context.require_permission(Some(account_id), Permission::DATA_READ)?;
-        Ok(Json(retrieve_email_content(account_id, envelope_id.0)?))
+        Ok(Json(retrieve_email_content(
+            account_id,
+            envelope_id.0,
+            block_remote,
+        )?))
     }
 
     /// Retrieves the content of an email embedded as an attachment.
@@ -152,15 +161,18 @@ impl MessageApi {
         /// The ID of the message to fetch.
         envelope_id: Path<String>,
         content_hash: Query<String>,
+        block_remote_content: Query<Option<bool>>,
         context: WrappedContext,
     ) -> ApiResult<Json<FullNestedMessageContent>> {
         let account_id = account_id.0;
+        let block_remote = block_remote_content.0.unwrap_or(false);
         context.require_permission(Some(account_id), Permission::DATA_READ)?;
         let content_hash = content_hash.0.trim();
         Ok(Json(retrieve_nested_eml_content(
             account_id,
             envelope_id.0,
             content_hash,
+            block_remote,
         )?))
     }
 
diff --git a/web/src/api/mailbox/envelope/api.ts b/web/src/api/mailbox/envelope/api.ts
index 552e9f6..a5a3dab 100644
--- a/web/src/api/mailbox/envelope/api.ts
+++ b/web/src/api/mailbox/envelope/api.ts
@@ -64,7 +64,8 @@ export interface AttachmentInfo {
 export interface MessageContentResponse {
     text?: string;
     html?: string;
-    attachments?: AttachmentInfo[]
+    attachments?: AttachmentInfo[];
+    has_remote_content?: boolean;
 }
 
 export interface NestedMessageContentResponse {
@@ -72,6 +73,7 @@ export interface NestedMessageContentResponse {
     html?: string;
     attachments?: AttachmentInfo[];
     envelope: EmailEnvelope;
+    has_remote_content?: boolean;
 }
 
 export const getContent = (messageContent: MessageContentResponse): string | null => {
@@ -83,13 +85,25 @@ export const getContent = (messageContent: MessageContentResponse): string | nul
     return null;
 };
 
-export const load_message = async (accountId: number, id: string) => {
-    const response = await axiosInstance.get<MessageContentResponse>(`api/v1/message-content/${accountId}/${id}`);
+export const load_message = async (accountId: number, id: string, blockRemoteContent = false) => {
+    const params = new URLSearchParams();
+    if (blockRemoteContent) {
+        params.set('block_remote_content', 'true');
+    }
+    const qs = params.toString();
+    const url = `api/v1/message-content/${accountId}/${id}${qs ? '?' + qs : ''}`;
+    const response = await axiosInstance.get<MessageContentResponse>(url);
     return response.data;
 };
 
-export const load_nested_message = async (accountId: number, id: string, content_hash: string) => {
-    const response = await axiosInstance.get<NestedMessageContentResponse>(`api/v1/nested-message-content/${accountId}/${id}?content_hash=${content_hash}`);
+export const load_nested_message = async (accountId: number, id: string, content_hash: string, blockRemoteContent = false) => {
+    const params = new URLSearchParams({ content_hash });
+    if (blockRemoteContent) {
+        params.set('block_remote_content', 'true');
+    }
+    const response = await axiosInstance.get<NestedMessageContentResponse>(
+        `api/v1/nested-message-content/${accountId}/${id}?${params.toString()}`
+    );
     return response.data;
 };
 
diff --git a/web/src/components/mail-iframe.tsx b/web/src/components/mail-iframe.tsx
index 9a62c11..a3b3962 100644
--- a/web/src/components/mail-iframe.tsx
+++ b/web/src/components/mail-iframe.tsx
@@ -31,7 +31,7 @@ const EmailIframe: React.FC<EmailIframeProps> = ({ emailHtml, height }) => {
   return (
     <iframe
       src={iframeSrc}
-      sandbox="allow-scripts"
+      sandbox=""
       className="w-full border-none"
       title="Email Content"
       style={{ height: height ?? '4000px' }}
diff --git a/web/src/features/attachment/mail-message-view.tsx b/web/src/features/attachment/mail-message-view.tsx
index a137f52..aa4648a 100644
--- a/web/src/features/attachment/mail-message-view.tsx
+++ b/web/src/features/attachment/mail-message-view.tsx
@@ -19,7 +19,7 @@
 
 import { useEffect, useState } from 'react';
 import { useMutation } from '@tanstack/react-query';
-import { Loader, Download, Trash2, MessageSquareMore, FileText, FileImage, FileVideo, FileArchive, FileSpreadsheet, FileCode, FileIcon, FileAudio, Upload } from 'lucide-react';
+import { Loader, Download, Trash2, MessageSquareMore, FileText, FileImage, FileVideo, FileArchive, FileSpreadsheet, FileCode, FileIcon, FileAudio, Upload, ShieldCheck } from 'lucide-react';
 
 import { Button } from '@/components/ui/button';
 import { Separator } from '@/components/ui/separator';
@@ -121,6 +121,12 @@ export function MailMessageView({
   const [nestedEmlFile, setNestedEmlFile] = useState<AttachmentInfo | null>(null);
   const { getEmailById } = useMinimalAccountList();
   const [threadOpen, setThreadOpen] = useState(false);
+  const [blockRemote, setBlockRemote] = useState(true);
+  const [hasRemoteContent, setHasRemoteContent] = useState(false);
+
+  const toggleBlockRemote = () => {
+    setBlockRemote((prev) => !prev);
+  };
 
   const downloadAttachmentMutation = useMutation({
     mutationFn: ({ content_hash }: { content_hash: string }) =>
@@ -137,12 +143,13 @@ export function MailMessageView({
   });
 
   const loadMessageMutation = useMutation({
-    mutationFn: () => load_message(envelope.account_id, envelope.id),
+    mutationFn: () => load_message(envelope.account_id, envelope.id, blockRemote),
     onSuccess: (data) => {
       setLoading(false);
       setContent(getContent(data));
       if (data.attachments) setAttachments(data.attachments);
       setContentType(data.html ? 'Html' : 'Plain');
+      setHasRemoteContent(!!data.has_remote_content);
     },
     onError: (error: any) => {
       setLoading(false);
@@ -154,10 +161,14 @@ export function MailMessageView({
     },
   });
 
+  useEffect(() => {
+    setBlockRemote(true);
+  }, [envelope.id]);
+
   useEffect(() => {
     setLoading(true);
     loadMessageMutation.mutate();
-  }, [envelope.id]);
+  }, [envelope.id, blockRemote]);
 
 
   const handleViewNestedEml = (attachment: AttachmentInfo) => {
@@ -376,6 +387,30 @@ export function MailMessageView({
         </div>
       )}
       {showAttachments && <Separator className="mb-2" />}
+      {hasRemoteContent && (
+        <div className="flex items-center justify-between bg-muted border px-3 py-1.5 mb-3 text-xs">
+          <div className="flex items-center gap-1.5 min-w-0">
+            <ShieldCheck className="h-3.5 w-3.5 text-muted-foreground shrink-0" />
+            {blockRemote ? (
+              <span className="text-muted-foreground truncate">
+                {t('mail.remoteBlocked', 'To protect your privacy, Bichon has blocked remote content in this message.')}
+              </span>
+            ) : (
+              <span className="text-muted-foreground truncate">
+                {t('mail.remoteShown', 'Remote content is now shown.')}
+              </span>
+            )}
+          </div>
+          <span
+            className="underline cursor-pointer hover:no-underline text-muted-foreground text-[11px] font-medium shrink-0 ml-2 select-none"
+            onClick={toggleBlockRemote}
+          >
+            {blockRemote
+              ? t('mail.showRemoteContent', 'Show remote content')
+              : t('mail.blockRemoteAgain', 'Block again')}
+          </span>
+        </div>
+      )}
       <div className="flex-1 overflow-auto">
         {loading ? (
           <div className="flex justify-center items-center py-8">
diff --git a/web/src/features/attachment/nested-email-dialog.tsx b/web/src/features/attachment/nested-email-dialog.tsx
index fe5146f..e32675e 100644
--- a/web/src/features/attachment/nested-email-dialog.tsx
+++ b/web/src/features/attachment/nested-email-dialog.tsx
@@ -150,7 +150,7 @@ export function NestedEmailDialog({ open, onOpenChange }: any) {
 
     const { data, isLoading } = useQuery({
         queryKey: ['nested-message', currentAttachment?.account_id!, currentAttachment?.envelope_id!, currentAttachment?.content_hash!],
-        queryFn: () => load_nested_message(currentAttachment?.account_id!, currentAttachment?.envelope_id!, currentAttachment?.content_hash!),
+        queryFn: () => load_nested_message(currentAttachment?.account_id!, currentAttachment?.envelope_id!, currentAttachment?.content_hash!, true),
         enabled: open && !!currentAttachment,
     });
 
diff --git a/web/src/features/search/mail-message-view.tsx b/web/src/features/search/mail-message-view.tsx
index bd3c24e..ea992d7 100644
--- a/web/src/features/search/mail-message-view.tsx
+++ b/web/src/features/search/mail-message-view.tsx
@@ -19,7 +19,7 @@
 
 import { useEffect, useState } from 'react';
 import { useMutation } from '@tanstack/react-query';
-import { Loader, Download, Trash2, MessageSquareMore, FileText, FileImage, FileVideo, FileArchive, FileSpreadsheet, FileCode, FileIcon, FileAudio, Upload } from 'lucide-react';
+import { Loader, Download, Trash2, MessageSquareMore, FileText, FileImage, FileVideo, FileArchive, FileSpreadsheet, FileCode, FileIcon, FileAudio, Upload, ShieldCheck } from 'lucide-react';
 
 import { Button } from '@/components/ui/button';
 import { Separator } from '@/components/ui/separator';
@@ -129,6 +129,12 @@ export function MailMessageView({
   const [nestedEmlFile, setNestedEmlFile] = useState<AttachmentInfo | null>(null);
   const { getEmailById } = useMinimalAccountList();
   const [threadOpen, setThreadOpen] = useState(false);
+  const [blockRemote, setBlockRemote] = useState(true);
+  const [hasRemoteContent, setHasRemoteContent] = useState(false);
+
+  const toggleBlockRemote = () => {
+    setBlockRemote((prev) => !prev);
+  };
 
   const downloadAttachmentMutation = useMutation({
     mutationFn: ({ content_hash }: { content_hash: string }) =>
@@ -145,12 +151,13 @@ export function MailMessageView({
   });
 
   const loadMessageMutation = useMutation({
-    mutationFn: () => load_message(envelope.account_id, envelope.id),
+    mutationFn: () => load_message(envelope.account_id, envelope.id, blockRemote),
     onSuccess: (data) => {
       setLoading(false);
       setContent(getContent(data));
       if (data.attachments) setAttachments(data.attachments);
       setContentType(data.html ? 'Html' : 'Plain');
+      setHasRemoteContent(!!data.has_remote_content);
     },
     onError: (error: any) => {
       setLoading(false);
@@ -162,10 +169,14 @@ export function MailMessageView({
     },
   });
 
+  useEffect(() => {
+    setBlockRemote(true);
+  }, [envelope.id]);
+
   useEffect(() => {
     setLoading(true);
     loadMessageMutation.mutate();
-  }, [envelope.id]);
+  }, [envelope.id, blockRemote]);
 
 
   const handleViewNestedEml = (attachment: AttachmentInfo) => {
@@ -384,6 +395,30 @@ export function MailMessageView({
         </div>
       )}
       {showAttachments && <Separator className="mb-2" />}
+      {hasRemoteContent && (
+        <div className="flex items-center justify-between bg-muted border px-3 py-1.5 mb-3 text-xs">
+          <div className="flex items-center gap-1.5 min-w-0">
+            <ShieldCheck className="h-3.5 w-3.5 text-muted-foreground shrink-0" />
+            {blockRemote ? (
+              <span className="text-muted-foreground truncate">
+                {t('mail.remoteBlocked', 'To protect your privacy, Bichon has blocked remote content in this message.')}
+              </span>
+            ) : (
+              <span className="text-muted-foreground truncate">
+                {t('mail.remoteShown', 'Remote content is now shown.')}
+              </span>
+            )}
+          </div>
+          <span
+            className="underline cursor-pointer hover:no-underline text-muted-foreground text-[11px] font-medium shrink-0 ml-2 select-none"
+            onClick={toggleBlockRemote}
+          >
+            {blockRemote
+              ? t('mail.showRemoteContent', 'Show remote content')
+              : t('mail.blockRemoteAgain', 'Block again')}
+          </span>
+        </div>
+      )}
       <div className="flex-1 overflow-auto">
         {loading ? (
           <div className="flex justify-center items-center py-8">
diff --git a/web/src/features/search/nested-email-dialog.tsx b/web/src/features/search/nested-email-dialog.tsx
index 404648b..49efd5e 100644
--- a/web/src/features/search/nested-email-dialog.tsx
+++ b/web/src/features/search/nested-email-dialog.tsx
@@ -148,7 +148,7 @@ export function NestedEmailDialog({ open, onOpenChange, accountId, envelopeId, f
 
     const { data, isLoading } = useQuery({
         queryKey: ['nested-message', accountId, envelopeId, content_hash],
-        queryFn: () => load_nested_message(accountId, envelopeId, content_hash),
+        queryFn: () => load_nested_message(accountId, envelopeId, content_hash, true),
         enabled: open && !!content_hash,
     });