diff --git a/legacy/core/src/main/java/com/fsck/k9/helper/FileHelper.java b/legacy/core/src/main/java/com/fsck/k9/helper/FileHelper.java
deleted file mode 100644
index 4c68b3077df..00000000000
--- a/legacy/core/src/main/java/com/fsck/k9/helper/FileHelper.java
+++ /dev/null
@@ -1,147 +0,0 @@
-package com.fsck.k9.helper;
-
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-
-import timber.log.Timber;
-
-import org.apache.commons.io.IOUtils;
-
-
-public class FileHelper {
-    public static void touchFile(final File parentDir, final String name) {
-        final File file = new File(parentDir, name);
-        try {
-            if (!file.exists()) {
-                if (!file.createNewFile()) {
-                    Timber.d("Unable to create file: %s", file.getAbsolutePath());
-                }
-            } else {
-                if (!file.setLastModified(System.currentTimeMillis())) {
-                    Timber.d("Unable to change last modification date: %s", file.getAbsolutePath());
-                }
-            }
-        } catch (Exception e) {
-            Timber.d(e, "Unable to touch file: %s", file.getAbsolutePath());
-        }
-    }
-
-    private static void copyFile(File from, File to) throws IOException {
-        FileInputStream in = new FileInputStream(from);
-        FileOutputStream out = new FileOutputStream(to);
-        try {
-            byte[] buffer = new byte[1024];
-            int count;
-            while ((count = in.read(buffer)) > 0) {
-                out.write(buffer, 0, count);
-            }
-            out.close();
-        } finally {
-            IOUtils.closeQuietly(in);
-            IOUtils.closeQuietly(out);
-        }
-    }
-
-    public static void renameOrMoveByCopying(File from, File to) throws IOException {
-        deleteFileIfExists(to);
-
-        boolean renameFailed = !from.renameTo(to);
-        if (renameFailed) {
-            copyFile(from, to);
-
-            boolean deleteFromFailed = !from.delete();
-            if (deleteFromFailed) {
-                Timber.e("Unable to delete source file after copying to destination!");
-            }
-        }
-    }
-
-    private static void deleteFileIfExists(File to) throws IOException {
-        boolean fileDoesNotExist = !to.exists();
-        if (fileDoesNotExist) {
-            return;
-        }
-
-        boolean deleteOk = to.delete();
-        if (deleteOk) {
-            return;
-        }
-
-        throw new IOException("Unable to delete file: " + to.getAbsolutePath());
-    }
-
-    public static boolean move(final File from, final File to) {
-        if (to.exists()) {
-            if (!to.delete()) {
-                Timber.d("Unable to delete file: %s", to.getAbsolutePath());
-            }
-        }
-
-        if (!to.getParentFile().mkdirs()) {
-            Timber.d("Unable to make directories: %s", to.getParentFile().getAbsolutePath());
-        }
-
-        try {
-            copyFile(from, to);
-
-            boolean deleteFromFailed = !from.delete();
-            if (deleteFromFailed) {
-                Timber.e("Unable to delete source file after copying to destination!");
-            }
-            return true;
-        } catch (Exception e) {
-            Timber.w(e, "cannot move %s to %s", from.getAbsolutePath(), to.getAbsolutePath());
-            return false;
-        }
-    }
-
-    public static void moveRecursive(final File fromDir, final File toDir) {
-        if (!fromDir.exists()) {
-            return;
-        }
-        if (!fromDir.isDirectory()) {
-            if (toDir.exists()) {
-                if (!toDir.delete()) {
-                    Timber.w("cannot delete already existing file/directory %s", toDir.getAbsolutePath());
-                }
-            }
-            if (!fromDir.renameTo(toDir)) {
-                Timber.w("cannot rename %s to %s - moving instead", fromDir.getAbsolutePath(), toDir.getAbsolutePath());
-                move(fromDir, toDir);
-            }
-            return;
-        }
-        if (!toDir.exists() || !toDir.isDirectory()) {
-            if (toDir.exists()) {
-                if (!toDir.delete()) {
-                    Timber.d("Unable to delete file: %s", toDir.getAbsolutePath());
-                }
-            }
-            if (!toDir.mkdirs()) {
-                Timber.w("cannot create directory %s", toDir.getAbsolutePath());
-            }
-        }
-        File[] files = fromDir.listFiles();
-        for (File file : files) {
-            if (file.isDirectory()) {
-                moveRecursive(file, new File(toDir, file.getName()));
-                if (!file.delete()) {
-                    Timber.d("Unable to delete file: %s", toDir.getAbsolutePath());
-                }
-            } else {
-                File target = new File(toDir, file.getName());
-                if (!file.renameTo(target)) {
-                    Timber.w("cannot rename %s to %s - moving instead",
-                            file.getAbsolutePath(), target.getAbsolutePath());
-                    move(file, target);
-                }
-            }
-        }
-        if (!fromDir.delete()) {
-            Timber.w("cannot delete %s", fromDir.getAbsolutePath());
-        }
-    }
-}
diff --git a/legacy/core/src/main/java/com/fsck/k9/helper/FileHelper.kt b/legacy/core/src/main/java/com/fsck/k9/helper/FileHelper.kt
new file mode 100644
index 00000000000..b79b75bd317
--- /dev/null
+++ b/legacy/core/src/main/java/com/fsck/k9/helper/FileHelper.kt
@@ -0,0 +1,73 @@
+package com.fsck.k9.helper
+
+import java.io.File
+import java.io.IOException
+import timber.log.Timber
+
+object FileHelper {
+
+    @JvmStatic
+    @Suppress("TooGenericExceptionCaught")
+    fun touchFile(parentDir: File, name: String) {
+        val file = File(parentDir, name)
+        try {
+            if (!file.exists()) {
+                if (!file.createNewFile()) {
+                    Timber.d("Unable to create file: %s", file.absolutePath)
+                }
+            } else {
+                if (!file.setLastModified(System.currentTimeMillis())) {
+                    Timber.d("Unable to change last modification date: %s", file.absolutePath)
+                }
+            }
+        } catch (e: Exception) {
+            Timber.d(e, "Unable to touch file: %s", file.absolutePath)
+        }
+    }
+
+    @JvmStatic
+    @Throws(IOException::class)
+    fun renameOrMoveByCopying(from: File, to: File) {
+        deleteFileIfExists(to)
+        val renameFailed = !from.renameTo(to)
+        if (renameFailed) {
+            from.copyTo(target = to, overwrite = true)
+            val deleteFromFailed = !from.delete()
+            if (deleteFromFailed) {
+                Timber.e("Unable to delete source file after copying to destination!")
+            }
+        }
+    }
+
+    @Throws(IOException::class)
+    private fun deleteFileIfExists(file: File) {
+        if (file.exists() && !file.delete()) {
+            throw IOException("Unable to delete file: ${file.absolutePath}")
+        }
+    }
+
+    @Suppress("TooGenericExceptionCaught")
+    fun move(from: File, to: File): Boolean {
+        if (to.exists()) {
+            if (!to.delete()) {
+                Timber.d("Unable to delete file: %s", to.absolutePath)
+            }
+        }
+
+        val parent = to.parentFile
+        if (parent != null && !parent.mkdirs()) {
+            Timber.d("Unable to make directories: %s", parent.absolutePath)
+        }
+        return try {
+            from.copyTo(target = to, overwrite = true)
+            val deleteFromFailed = !from.delete()
+            if (deleteFromFailed) {
+                Timber.e("Unable to delete source file after copying to destination!")
+            }
+            true
+        } catch (e: Exception) {
+            Timber.w(e, "cannot move %s to %s", from.absolutePath, to.absolutePath)
+            false
+        }
+    }
+}
diff --git a/legacy/core/src/test/java/com/fsck/k9/helper/FileHelperTest.kt b/legacy/core/src/test/java/com/fsck/k9/helper/FileHelperTest.kt
new file mode 100644
index 00000000000..5b5d3a4b3b0
--- /dev/null
+++ b/legacy/core/src/test/java/com/fsck/k9/helper/FileHelperTest.kt
@@ -0,0 +1,68 @@
+package com.fsck.k9.helper
+
+import assertk.assertThat
+import assertk.assertions.isEqualTo
+import assertk.assertions.isFalse
+import assertk.assertions.isNotEqualTo
+import assertk.assertions.isTrue
+import java.io.File
+import kotlin.test.Test
+import org.junit.Rule
+import org.junit.rules.TemporaryFolder
+
+class FileHelperTest {
+
+    @Rule
+    @JvmField
+    val tempFolder = TemporaryFolder()
+
+    @Test
+    fun `touchFile should create file`() {
+        val parent = tempFolder.newFolder("parent")
+
+        FileHelper.touchFile(parent, "FileName")
+
+        assertThat(File(parent, "FileName").exists()).isTrue()
+    }
+
+    @Test
+    fun `touchFile should change file modification time`() {
+        val parent = tempFolder.newFolder("parent")
+        val lastModified = 12345L
+        val file = File(parent, "FileName")
+        file.createNewFile()
+        file.setLastModified(lastModified)
+
+        FileHelper.touchFile(parent, "FileName")
+
+        assertThat(file.lastModified()).isNotEqualTo(lastModified)
+    }
+
+    @Test
+    fun `renameOrMoveByCopying should move file when destination does not exist`() {
+        val source = tempFolder.newFile("source")
+        val destination = File(tempFolder.root, "destination")
+        val sourceContent = "content"
+        source.writeText(sourceContent)
+
+        FileHelper.renameOrMoveByCopying(source, destination)
+
+        assertThat(source.exists()).isFalse()
+        assertThat(destination.exists()).isTrue()
+        assertThat(destination.readText()).isEqualTo(sourceContent)
+    }
+
+    @Test
+    fun `renameOrMoveByCopying should move file when destination exists`() {
+        val source = tempFolder.newFile("source")
+        val destination = tempFolder.newFile("destination")
+        val sourceContent = "content"
+        source.writeText(sourceContent)
+
+        FileHelper.renameOrMoveByCopying(source, destination)
+
+        assertThat(source.exists()).isFalse()
+        assertThat(destination.exists()).isTrue()
+        assertThat(destination.readText()).isEqualTo(sourceContent)
+    }
+}