diff --git a/src/api/__tests__/blob.test.ts b/src/api/__tests__/blob.test.ts
index 4fc03585..7fa818a3 100644
--- a/src/api/__tests__/blob.test.ts
+++ b/src/api/__tests__/blob.test.ts
@@ -40,7 +40,7 @@ vi.mock('../jmap-client', () => ({
   },
 }));
 
-import { getDownloadUrl, uploadBlob } from '../blob';
+import { getDownloadUrl, isStaleUploadCopy, uploadBlob } from '../blob';
 
 beforeEach(() => {
   vi.clearAllMocks();
@@ -165,3 +165,23 @@ describe('uploadBlob', () => {
     expect(createUploadTask).not.toHaveBeenCalled();
   });
 });
+
+describe('isStaleUploadCopy', () => {
+  it('flags upload copies an earlier run of the app left behind', () => {
+    expect(isStaleUploadCopy('upload-1700000000000-3')).toBe(true);
+  });
+
+  it("leaves this run's copies alone, since they may still be uploading", async () => {
+    uploadTask.uploadAsync.mockResolvedValueOnce({ status: 200, body: JSON.stringify({ blobId: 'b' }) });
+    await uploadBlob('content://com.example.provider/doc/9', 'image/png');
+    const name = copyAsync.mock.calls[0][0].to.replace('file:///cache/', '');
+
+    expect(isStaleUploadCopy(name)).toBe(false);
+  });
+
+  it('ignores other cache files', () => {
+    expect(isStaleUploadCopy('upload-notes.txt')).toBe(false);
+    expect(isStaleUploadCopy('bulwark-exports')).toBe(false);
+    expect(isStaleUploadCopy('x-upload-1700000000000-3')).toBe(false);
+  });
+});
diff --git a/src/api/blob.ts b/src/api/blob.ts
index ba88c492..93b6d5a4 100644
--- a/src/api/blob.ts
+++ b/src/api/blob.ts
@@ -107,6 +107,18 @@ export async function uploadBlob(
 }
 
 let cacheCopySeq = 0;
+const UPLOAD_COPY_NAME = /^upload-(\d+)-\d+$/;
+const loadedAt = Date.now();
+
+/**
+ * Whether a cache file is an upload copy (see below) made by an earlier run
+ * of the app: one killed mid-upload never deleted it. Copies of this run may
+ * still be uploading and are left alone.
+ */
+export function isStaleUploadCopy(name: string): boolean {
+  const match = UPLOAD_COPY_NAME.exec(name);
+  return !!match && Number(match[1]) < loadedAt;
+}
 
 // The native upload task reads from a file path, but files shared into the
 // app from another app arrive as Android `content://` URIs with nothing on
diff --git a/src/lib/__tests__/email-export.test.ts b/src/lib/__tests__/email-export.test.ts
index 3244c6e5..47308cd4 100644
--- a/src/lib/__tests__/email-export.test.ts
+++ b/src/lib/__tests__/email-export.test.ts
@@ -65,7 +65,10 @@ vi.mock('expo-file-system', () => {
   return {
     File,
     Directory,
-    Paths: { cache: { uri: 'file:///cache/' }, document: { uri: 'file:///documents/' } },
+    Paths: {
+      cache: { uri: 'file:///cache/', list: () => fsState.listings.get('file:///cache/') ?? [] },
+      document: { uri: 'file:///documents/' },
+    },
   };
 });
 
@@ -97,6 +100,7 @@ vi.mock('../../api/jmap-client', () => ({
 
 vi.mock('../../api/blob', () => ({
   getDownloadUrl: vi.fn((blobId: string, name: string) => `https://mail.example.com/${blobId}/${name}`),
+  isStaleUploadCopy: (name: string) => name.startsWith('upload-old-'),
 }));
 
 import * as IntentLauncher from 'expo-intent-launcher';
@@ -356,4 +360,19 @@ describe('sweepStaleExportFiles', () => {
       handedOff.uri,
     ]);
   });
+
+  it('removes the upload copies an earlier run left in the cache', async () => {
+    vi.resetModules();
+    const fsMod = await import('expo-file-system');
+    const { sweepStaleExportFiles } = await import('../email-export');
+    fsState.deleted.length = 0;
+    fsState.listings.clear();
+    const cache = { uri: 'file:///cache/' };
+    fsState.listings.set(cache.uri, ['upload-old-1', 'upload-current-2', 'image-cache.png']
+      .map((name) => new fsMod.File(cache as never, name)));
+
+    await sweepStaleExportFiles();
+
+    expect(fsState.deleted).toEqual(['file:///cache/upload-old-1']);
+  });
 });
diff --git a/src/lib/email-export.ts b/src/lib/email-export.ts
index 0469192d..777defbb 100644
--- a/src/lib/email-export.ts
+++ b/src/lib/email-export.ts
@@ -3,7 +3,7 @@ import { Directory, File, Paths } from 'expo-file-system';
 import * as IntentLauncher from 'expo-intent-launcher';
 import * as Sharing from 'expo-sharing';
 import { jmapClient } from '../api/jmap-client';
-import { getDownloadUrl } from '../api/blob';
+import { getDownloadUrl, isStaleUploadCopy } from '../api/blob';
 import type { Attachment, Email } from '../api/types';
 import { useSettingsStore } from '../stores/settings-store';
 import {
@@ -89,13 +89,20 @@ function deleteStaleFiles(dir: Directory, now: number, maxAgeMs: number): void {
  * Remove temp files older than a day. Files shared into other apps could not
  * always be deleted right after the share sheet closed (the receiving app may
  * still be reading them), so anything that slipped through is collected here,
- * including preview folders whose file went to another app. Runs once per
- * process, lazily before the first export, and is also safe to call at launch.
+ * including preview folders whose file went to another app. Also removes the
+ * cache copies of shared files that an earlier run was killed while uploading
+ * (`api/blob`). Runs once per process, lazily before the first export, and is
+ * also safe to call at launch.
  */
 let sweptThisProcess = false;
 export async function sweepStaleExportFiles(maxAgeMs = STALE_EXPORT_MS): Promise<void> {
   if (sweptThisProcess) return;
   sweptThisProcess = true;
+  try {
+    for (const entry of Paths.cache.list()) {
+      if (entry instanceof File && isStaleUploadCopy(entry.name)) deleteQuietly(entry);
+    }
+  } catch { /* housekeeping only */ }
   try {
     const dir = exportsDir();
     if (!dir.exists) return;