diff --git a/ATTRIBUTION.md b/ATTRIBUTION.md
index 975f75893e..21f71df1d0 100644
--- a/ATTRIBUTION.md
+++ b/ATTRIBUTION.md
@@ -47,3 +47,4 @@ FairEmail uses:
 * [MaterialDings](https://github.com/Accusoft/MaterialDings). Copyright (c) 2018 Accusoft Corporation. [MIT License](https://github.com/Accusoft/MaterialDings/blob/master/LICENSE.md).
 * [Send](https://github.com/timvisee/send). [Mozilla Public License 2.0](https://github.com/timvisee/send/blob/master/LICENSE).
 * [DetectHtml](https://github.com/dbennett455/DetectHtml). [The MIT License](https://github.com/dbennett455/DetectHtml/blob/master/LICENSE).
+* [Elephant Bird](https://github.com/twitter/elephant-bird). [Apache License Version 2.0](https://github.com/twitter/elephant-bird/blob/master/LICENSE).
diff --git a/app/src/main/assets/ATTRIBUTION.md b/app/src/main/assets/ATTRIBUTION.md
index 975f75893e..21f71df1d0 100644
--- a/app/src/main/assets/ATTRIBUTION.md
+++ b/app/src/main/assets/ATTRIBUTION.md
@@ -47,3 +47,4 @@ FairEmail uses:
 * [MaterialDings](https://github.com/Accusoft/MaterialDings). Copyright (c) 2018 Accusoft Corporation. [MIT License](https://github.com/Accusoft/MaterialDings/blob/master/LICENSE.md).
 * [Send](https://github.com/timvisee/send). [Mozilla Public License 2.0](https://github.com/timvisee/send/blob/master/LICENSE).
 * [DetectHtml](https://github.com/dbennett455/DetectHtml). [The MIT License](https://github.com/dbennett455/DetectHtml/blob/master/LICENSE).
+* [Elephant Bird](https://github.com/twitter/elephant-bird). [Apache License Version 2.0](https://github.com/twitter/elephant-bird/blob/master/LICENSE).
diff --git a/app/src/main/java/com/twitter/elephantbird/util/StreamSearcher.java b/app/src/main/java/com/twitter/elephantbird/util/StreamSearcher.java
new file mode 100644
index 0000000000..a914aba425
--- /dev/null
+++ b/app/src/main/java/com/twitter/elephantbird/util/StreamSearcher.java
@@ -0,0 +1,87 @@
+package com.twitter.elephantbird.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+
+/**
+ * An efficient stream searching class based on the Knuth-Morris-Pratt algorithm.
+ * For more on the algorithm works see: https://www.inf.fh-flensburg.de/lang/algorithmen/pattern/kmpen.htm.
+ */
+public class StreamSearcher {
+
+  protected byte[] pattern_;
+  protected int[] borders_;
+
+  // An upper bound on pattern length for searching. Results are undefined for longer patterns.
+  public static final int MAX_PATTERN_LENGTH = 1024;
+
+  public StreamSearcher(byte[] pattern) {
+    setPattern(pattern);
+  }
+
+  /**
+   * Sets a new pattern for this StreamSearcher to use.
+   * @param pattern
+   *          the pattern the StreamSearcher will look for in future calls to search(...)
+   */
+  public void setPattern(byte[] pattern) {
+    pattern_ = Arrays.copyOf(pattern, pattern.length);
+    borders_ = new int[pattern_.length + 1];
+    preProcess();
+  }
+
+  /**
+   * Searches for the next occurrence of the pattern in the stream, starting from the current stream position. Note
+   * that the position of the stream is changed. If a match is found, the stream points to the end of the match -- i.e. the
+   * byte AFTER the pattern. Else, the stream is entirely consumed. The latter is because InputStream semantics make it difficult to have
+   * another reasonable default, i.e. leave the stream unchanged.
+   *
+   * @return bytes consumed if found, -1 otherwise.
+   * @throws IOException
+   */
+  public long search(InputStream stream) throws IOException {
+    long bytesRead = 0;
+
+    int b;
+    int j = 0;
+
+    while ((b = stream.read()) != -1) {
+      bytesRead++;
+
+      while (j >= 0 && (byte)b != pattern_[j]) {
+        j = borders_[j];
+      }
+      // Move to the next character in the pattern.
+      ++j;
+
+      // If we've matched up to the full pattern length, we found it.  Return,
+      // which will automatically save our position in the InputStream at the point immediately
+      // following the pattern match.
+      if (j == pattern_.length) {
+        return bytesRead;
+      }
+    }
+
+    // No dice, Note that the stream is now completely consumed.
+    return -1;
+  }
+
+  /**
+   * Builds up a table of longest "borders" for each prefix of the pattern to find. This table is stored internally
+   * and aids in implementation of the Knuth-Moore-Pratt string search.
+   * <p>
+   * For more information, see: https://www.inf.fh-flensburg.de/lang/algorithmen/pattern/kmpen.htm.
+   */
+  protected void preProcess() {
+    int i = 0;
+    int j = -1;
+    borders_[i] = j;
+    while (i < pattern_.length) {
+      while (j >= 0 && pattern_[i] != pattern_[j]) {
+        j = borders_[j];
+      }
+      borders_[++i] = ++j;
+    }
+  }
+}
diff --git a/app/src/main/java/eu/faircode/email/ActivityView.java b/app/src/main/java/eu/faircode/email/ActivityView.java
index fb4bf2fb61..fca4b71358 100644
--- a/app/src/main/java/eu/faircode/email/ActivityView.java
+++ b/app/src/main/java/eu/faircode/email/ActivityView.java
@@ -2427,6 +2427,7 @@ public class ActivityView extends ActivityBilling implements FragmentManager.OnB
             criteria.in_subject = false;
             criteria.in_keywords = false;
             criteria.in_message = false;
+            criteria.in_attachments = false;
             criteria.in_notes = false;
         }
 
diff --git a/app/src/main/java/eu/faircode/email/AdapterFolder.java b/app/src/main/java/eu/faircode/email/AdapterFolder.java
index 20fb340d84..d8ecff579c 100644
--- a/app/src/main/java/eu/faircode/email/AdapterFolder.java
+++ b/app/src/main/java/eu/faircode/email/AdapterFolder.java
@@ -525,6 +525,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
             criteria.in_subject = false;
             criteria.in_keywords = false;
             criteria.in_message = false;
+            criteria.in_attachments = false;
             criteria.in_notes = false;
             criteria.with_unseen = true;
             FragmentMessages.search(
@@ -539,6 +540,7 @@ public class AdapterFolder extends RecyclerView.Adapter<AdapterFolder.ViewHolder
             criteria.in_subject = false;
             criteria.in_keywords = false;
             criteria.in_message = false;
+            criteria.in_attachments = false;
             criteria.in_notes = false;
             criteria.with_flagged = true;
             FragmentMessages.search(
diff --git a/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java b/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java
index f4cf561ebe..ecdf251eb9 100644
--- a/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java
+++ b/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java
@@ -39,6 +39,7 @@ import com.sun.mail.imap.protocol.IMAPProtocol;
 import com.sun.mail.imap.protocol.IMAPResponse;
 import com.sun.mail.imap.protocol.SearchSequence;
 import com.sun.mail.util.MessageRemovedIOException;
+import com.twitter.elephantbird.util.StreamSearcher;
 
 import org.json.JSONArray;
 import org.json.JSONException;
@@ -46,9 +47,12 @@ import org.json.JSONObject;
 import org.jsoup.nodes.Document;
 
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.Serializable;
 import java.lang.reflect.Constructor;
+import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.text.Normalizer;
 import java.util.ArrayList;
@@ -341,6 +345,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                         //criteria.in_subject,
                         //criteria.in_keywords,
                         //criteria.in_message,
+                        //criteria.in_attachments,
                         //criteria.in_notes,
                         //criteria.in_headers,
                         criteria.with_unseen,
@@ -866,6 +871,37 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                 Log.e(ex);
             }
 
+        if (criteria.in_attachments && !TextUtils.isEmpty(criteria.query))
+            try {
+                DB db = DB.getInstance(context);
+                List<EntityAttachment> attachments = db.attachment().getAttachments(message.id);
+                if (attachments != null)
+                    for (EntityAttachment attachment : attachments) {
+                        File file = attachment.getFile(context);
+                        if (file.exists() && file.length() > 0) {
+                            byte[] sample = new byte[(int) Math.min(4096, file.length())];
+                            try (InputStream is = new FileInputStream(file)) {
+                                Helper.readBuffer(is, sample);
+                            }
+
+                            Charset detected = CharsetHelper.detect(sample, null);
+                            if (detected == null)
+                                detected = StandardCharsets.ISO_8859_1;
+
+                            Log.i("Searching for " + criteria.query +
+                                    " as " + detected +
+                                    " in " + file.getName() + ":" + file.length());
+                            try (InputStream is = new FileInputStream(file)) {
+                                StreamSearcher searcher = new StreamSearcher(criteria.query.getBytes(detected));
+                                if (searcher.search(is) > 0)
+                                    return true;
+                            }
+                        }
+                    }
+            } catch (Throwable ex) {
+                Log.e(ex);
+            }
+
         return false;
     }
 
@@ -987,6 +1023,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
         boolean in_subject = true;
         boolean in_keywords = true;
         boolean in_message = true;
+        boolean in_attachments = false;
         boolean in_notes = true;
         boolean in_headers = false;
         boolean in_html = false;
@@ -1272,6 +1309,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                         this.in_subject == other.in_subject &&
                         this.in_keywords == other.in_keywords &&
                         this.in_message == other.in_message &&
+                        this.in_attachments == other.in_attachments &&
                         this.in_notes == other.in_notes &&
                         this.in_headers == other.in_headers &&
                         this.in_html == other.in_html &&
@@ -1300,6 +1338,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
             json.put("in_subject", in_subject);
             json.put("in_keywords", in_keywords);
             json.put("in_message", in_message);
+            json.put("in_attachments", in_attachments);
             json.put("in_notes", in_notes);
             json.put("in_headers", in_headers);
             json.put("in_html", in_html);
@@ -1347,6 +1386,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
             criteria.in_subject = json.optBoolean("in_subject");
             criteria.in_keywords = json.optBoolean("in_keywords");
             criteria.in_message = json.optBoolean("in_message");
+            criteria.in_attachments = json.optBoolean("in_attachments");
             criteria.in_notes = json.optBoolean("in_notes");
             criteria.in_headers = json.optBoolean("in_headers");
             criteria.in_html = json.optBoolean("in_html");
@@ -1395,6 +1435,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                     " subject=" + in_subject +
                     " keywords=" + in_keywords +
                     " message=" + in_message +
+                    " attachment=" + in_attachments +
                     " notes=" + in_notes +
                     " headers=" + in_headers +
                     " html=" + in_html +
diff --git a/app/src/main/java/eu/faircode/email/CharsetHelper.java b/app/src/main/java/eu/faircode/email/CharsetHelper.java
index daaeaf8e97..2e2ec8cd34 100644
--- a/app/src/main/java/eu/faircode/email/CharsetHelper.java
+++ b/app/src/main/java/eu/faircode/email/CharsetHelper.java
@@ -225,19 +225,7 @@ public class CharsetHelper {
 
         try {
             byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);
-
-            byte[] sample;
-            if (octets.length < MAX_SAMPLE_SIZE)
-                sample = octets;
-            else {
-                sample = new byte[MAX_SAMPLE_SIZE];
-                System.arraycopy(octets, 0, sample, 0, MAX_SAMPLE_SIZE);
-            }
-
-            Log.i("compact_enc_det sample=" + sample.length);
-            DetectResult detected = jni_detect_charset(sample,
-                    ref == null ? StandardCharsets.ISO_8859_1.name() : ref.name(),
-                    Locale.getDefault().getLanguage());
+            DetectResult detected = _detect(octets, ref);
 
             if (TextUtils.isEmpty(detected.charset)) {
                 Log.e("compact_enc_det result=" + detected);
@@ -262,7 +250,34 @@ public class CharsetHelper {
         }
     }
 
-    private static class DetectResult {
+    public static Charset detect(byte[] octets, Charset ref) {
+        try {
+            DetectResult detected = _detect(octets, ref);
+            if (TextUtils.isEmpty(detected.charset))
+                return null;
+            return Charset.forName(detected.charset);
+        } catch (Throwable ex) {
+            Log.w(ex);
+            return null;
+        }
+    }
+
+    private static DetectResult _detect(byte[] octets, Charset ref) {
+        byte[] sample;
+        if (octets.length < MAX_SAMPLE_SIZE)
+            sample = octets;
+        else {
+            sample = new byte[MAX_SAMPLE_SIZE];
+            System.arraycopy(octets, 0, sample, 0, MAX_SAMPLE_SIZE);
+        }
+
+        Log.i("compact_enc_det sample=" + sample.length);
+        return jni_detect_charset(sample,
+                ref == null ? StandardCharsets.ISO_8859_1.name() : ref.name(),
+                Locale.getDefault().getLanguage());
+    }
+
+    public static class DetectResult {
         String charset;
         int sample_size;
         int bytes_consumed;
diff --git a/app/src/main/java/eu/faircode/email/FragmentDialogSearch.java b/app/src/main/java/eu/faircode/email/FragmentDialogSearch.java
index 4ab9d21c09..79c6a0761f 100644
--- a/app/src/main/java/eu/faircode/email/FragmentDialogSearch.java
+++ b/app/src/main/java/eu/faircode/email/FragmentDialogSearch.java
@@ -114,6 +114,7 @@ public class FragmentDialogSearch extends FragmentDialogBase {
         CheckBox cbKeywords = dview.findViewById(R.id.cbKeywords);
         CheckBox cbMessage = dview.findViewById(R.id.cbMessage);
         TextView tvSearchTextUnsupported = dview.findViewById(R.id.tvSearchTextUnsupported);
+        CheckBox cbAttachments = dview.findViewById(R.id.cbAttachments);
         CheckBox cbNotes = dview.findViewById(R.id.cbNotes);
         CheckBox cbHeaders = dview.findViewById(R.id.cbHeaders);
         CheckBox cbHtml = dview.findViewById(R.id.cbHtml);
@@ -123,7 +124,7 @@ public class FragmentDialogSearch extends FragmentDialogBase {
         CheckBox cbFlagged = dview.findViewById(R.id.cbFlagged);
         CheckBox cbHidden = dview.findViewById(R.id.cbHidden);
         CheckBox cbEncrypted = dview.findViewById(R.id.cbEncrypted);
-        CheckBox cbAttachments = dview.findViewById(R.id.cbAttachments);
+        CheckBox cbWithAttachments = dview.findViewById(R.id.cbWithAttachments);
         Spinner spMessageSize = dview.findViewById(R.id.spMessageSize);
         Button btnBefore = dview.findViewById(R.id.btnBefore);
         Button btnAfter = dview.findViewById(R.id.btnAfter);
@@ -430,6 +431,7 @@ public class FragmentDialogSearch extends FragmentDialogBase {
                         criteria.in_subject = cbSubject.isChecked();
                         criteria.in_keywords = cbKeywords.isChecked();
                         criteria.in_message = cbMessage.isChecked();
+                        criteria.in_attachments = cbAttachments.isChecked();
                         criteria.in_notes = cbNotes.isChecked();
                         criteria.in_headers = cbHeaders.isChecked();
                         criteria.in_html = cbHtml.isChecked();
@@ -437,7 +439,7 @@ public class FragmentDialogSearch extends FragmentDialogBase {
                         criteria.with_flagged = cbFlagged.isChecked();
                         criteria.with_hidden = cbHidden.isChecked();
                         criteria.with_encrypted = cbEncrypted.isChecked();
-                        criteria.with_attachments = cbAttachments.isChecked();
+                        criteria.with_attachments = cbWithAttachments.isChecked();
 
                         if (!criteria.fts) {
                             int pos = spMessageSize.getSelectedItemPosition();
diff --git a/app/src/main/res/layout/dialog_search.xml b/app/src/main/res/layout/dialog_search.xml
index 9a43594707..dffb408686 100644
--- a/app/src/main/res/layout/dialog_search.xml
+++ b/app/src/main/res/layout/dialog_search.xml
@@ -337,6 +337,29 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/tvSearchTextHint" />
 
+        <CheckBox
+            android:id="@+id/cbAttachments"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="@string/title_search_in_attachments"
+            android:textAppearance="@style/TextAppearance.AppCompat.Medium"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvSearchTextUnsupported" />
+
+        <TextView
+            android:id="@+id/tvSearchAttachmentsHint"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="6dp"
+            android:text="@string/title_search_attachments_hint"
+            android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textStyle="italic"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/cbAttachments" />
+
         <CheckBox
             android:id="@+id/cbNotes"
             android:layout_width="0dp"
@@ -347,7 +370,7 @@
             android:textAppearance="@style/TextAppearance.AppCompat.Medium"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/tvSearchTextUnsupported" />
+            app:layout_constraintTop_toBottomOf="@id/tvSearchAttachmentsHint" />
 
         <CheckBox
             android:id="@+id/cbHeaders"
@@ -450,7 +473,7 @@
             app:layout_constraintTop_toBottomOf="@id/cbHidden" />
 
         <CheckBox
-            android:id="@+id/cbAttachments"
+            android:id="@+id/cbWithAttachments"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:layout_marginTop="12dp"
@@ -470,7 +493,7 @@
             android:visibility="gone"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/cbAttachments" />
+            app:layout_constraintTop_toBottomOf="@id/cbWithAttachments" />
 
         <Spinner
             android:id="@+id/spMessageSize"
@@ -569,8 +592,11 @@
             android:layout_width="0dp"
             android:layout_height="0dp"
             app:constraint_referenced_ids="
-            cbSearchIndex,tvSearchIndexHint,cbSenders,cbRecipients,cbSubject,cbKeywords,cbMessage,tvSearchTextHint,tvSearchTextUnsupported,cbNotes,
-            tvAnd,cbUnseen,cbFlagged,cbHidden,cbEncrypted,cbAttachments,
+            cbSearchIndex,tvSearchIndexHint,
+            cbSenders,cbRecipients,cbSubject,cbKeywords,
+            cbMessage,tvSearchTextHint,tvSearchTextUnsupported,
+            cbAttachments,tvSearchAttachmentsHint,cbNotes,
+            tvAnd,cbUnseen,cbFlagged,cbHidden,cbEncrypted,cbWithAttachments,
             tvDate,btnAfter,btnBefore,tvBefore,tvAfter,cbSearchDevice" />
     </androidx.constraintlayout.widget.ConstraintLayout>
 </eu.faircode.email.ScrollViewEx>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index a2bdcf7e36..c40fc89220 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1763,6 +1763,7 @@
     <string name="title_search_index_hint">Searching via the search index is fast, but only finds whole words.</string>
     <string name="title_search_text_hint">Searching for text in messages, when there are a large number of messages, might not work on some servers</string>
     <string name="title_search_text_unsupported">\'%s\' means that the mail server doesn\'t support searching in message texts</string>
+    <string name="title_search_attachments_hint">This will be slow when there are many or large attachments</string>
     <string name="title_search_size_hint">Searching for messages by size, when there are a large number of messages, might not work on some servers</string>
     <string name="title_search_more">More options</string>
     <string name="title_search_use_index">Use search index</string>
@@ -1771,6 +1772,7 @@
     <string name="title_search_in_subject">In subject</string>
     <string name="title_search_in_keywords">In keywords (if supported)</string>
     <string name="title_search_in_message">In message text</string>
+    <string name="title_search_in_attachments">In attachments (on device only)</string>
     <string name="title_search_in_notes">In local notes</string>
     <string name="title_search_in_headers" translatable="false">In headers</string>
     <string name="title_search_in_html" translatable="false">In HTML</string>