diff --git a/components/email/email-viewer.tsx b/components/email/email-viewer.tsx
index 5060f5b4..8ff180b1 100644
--- a/components/email/email-viewer.tsx
+++ b/components/email/email-viewer.tsx
@@ -905,6 +905,24 @@ export function EmailViewer({
   const dragOutActive = useMemo(() => isDragOutSupported(), []);
   const emailDownloadTemplate = useSettingsStore((state) => state.emailDownloadTemplate) || DEFAULT_EMAIL_TEMPLATE;
   const attachmentDownloadTemplate = useSettingsStore((state) => state.attachmentDownloadTemplate) || DEFAULT_ATTACHMENT_TEMPLATE;
+  const filenameSpaceReplacement = useSettingsStore((state) => state.filenameSpaceReplacement);
+  const filenameLowercase = useSettingsStore((state) => state.filenameLowercase);
+  const filenameStripDiacritics = useSettingsStore((state) => state.filenameStripDiacritics);
+  const filenameCollapseSeparators = useSettingsStore((state) => state.filenameCollapseSeparators);
+  const emailFilenameOptions = useMemo(() => ({
+    template: emailDownloadTemplate,
+    spaceReplacement: filenameSpaceReplacement,
+    lowercase: filenameLowercase,
+    stripDiacritics: filenameStripDiacritics,
+    collapseSeparators: filenameCollapseSeparators,
+  }), [emailDownloadTemplate, filenameSpaceReplacement, filenameLowercase, filenameStripDiacritics, filenameCollapseSeparators]);
+  const attachmentFilenameOptions = useMemo(() => ({
+    template: attachmentDownloadTemplate,
+    spaceReplacement: filenameSpaceReplacement,
+    lowercase: filenameLowercase,
+    stripDiacritics: filenameStripDiacritics,
+    collapseSeparators: filenameCollapseSeparators,
+  }), [attachmentDownloadTemplate, filenameSpaceReplacement, filenameLowercase, filenameStripDiacritics, filenameCollapseSeparators]);
   const timeFormat = useSettingsStore((state) => state.timeFormat);
   const isFocusedMailLayout = mailLayout === 'focus';
 
@@ -2569,9 +2587,9 @@ export function EmailViewer({
     (attachment: EffectiveAttachment) => {
       const fallback = attachment.name || 'download';
       if (!email) return fallback;
-      return attachmentDownloadFilename(email, { name: attachment.name, type: attachment.type }, attachmentDownloadTemplate) || fallback;
+      return attachmentDownloadFilename(email, { name: attachment.name, type: attachment.type }, attachmentFilenameOptions) || fallback;
     },
-    [email, attachmentDownloadTemplate],
+    [email, attachmentFilenameOptions],
   );
 
   const handleEffectiveAttachmentOpen = useCallback(async (attachment: EffectiveAttachment) => {
@@ -3072,7 +3090,7 @@ export function EmailViewer({
   const handleExportEmail = async () => {
     if (!email?.blobId || !client) return;
     try {
-      await client.downloadBlob(email.blobId, emailExportFilename(email, emailDownloadTemplate), 'message/rfc822');
+      await client.downloadBlob(email.blobId, emailExportFilename(email, emailFilenameOptions), 'message/rfc822');
     } catch {
       toast.error(tNotifications('export_email_error'));
     }
diff --git a/components/settings/downloads-settings.tsx b/components/settings/downloads-settings.tsx
index 1f6406c2..eabf46e3 100644
--- a/components/settings/downloads-settings.tsx
+++ b/components/settings/downloads-settings.tsx
@@ -3,7 +3,7 @@
 import { useMemo, useRef } from "react";
 import { useTranslations } from "next-intl";
 import { useSettingsStore } from "@/stores/settings-store";
-import { SettingsSection } from "./settings-section";
+import { SettingsSection, SettingItem, Select, ToggleSwitch } from "./settings-section";
 import { RotateCcw } from "lucide-react";
 import { cn } from "@/lib/utils";
 import {
@@ -14,6 +14,7 @@ import {
   emailExportFilename,
   attachmentDownloadFilename,
   buildSampleEmail,
+  type EmailFilenameOptions,
 } from "@/lib/download-filename";
 
 function insertTokenAtCursor(
@@ -46,6 +47,7 @@ interface TemplateEditorProps {
   preview: string;
   onChange: (next: string) => void;
   resetLabel: string;
+  previewLabel: string;
   placeholder?: string;
 }
 
@@ -58,6 +60,7 @@ function TemplateEditor({
   preview,
   onChange,
   resetLabel,
+  previewLabel,
   placeholder,
 }: TemplateEditorProps) {
   const inputRef = useRef<HTMLInputElement>(null);
@@ -114,7 +117,7 @@ function TemplateEditor({
           ))}
         </div>
         <div className="text-xs text-muted-foreground">
-          <span className="opacity-70">Preview: </span>
+          <span className="opacity-70">{previewLabel} </span>
           <span className="font-mono text-foreground/90 break-all">{preview}</span>
         </div>
       </div>
@@ -124,23 +127,45 @@ function TemplateEditor({
 
 export function DownloadsSettings() {
   const t = useTranslations("settings.downloads");
-  const { emailDownloadTemplate, attachmentDownloadTemplate, updateSetting } = useSettingsStore();
+  const {
+    emailDownloadTemplate,
+    attachmentDownloadTemplate,
+    filenameSpaceReplacement,
+    filenameLowercase,
+    filenameStripDiacritics,
+    filenameCollapseSeparators,
+    updateSetting,
+  } = useSettingsStore();
 
   const sampleEmail = useMemo(() => buildSampleEmail(), []);
   const sampleAttachment = useMemo(() => ({ name: "Invoice-2026-05.pdf", type: "application/pdf" }), []);
 
+  const transform = useMemo(
+    () => ({
+      spaceReplacement: filenameSpaceReplacement,
+      lowercase: filenameLowercase,
+      stripDiacritics: filenameStripDiacritics,
+      collapseSeparators: filenameCollapseSeparators,
+    }),
+    [filenameSpaceReplacement, filenameLowercase, filenameStripDiacritics, filenameCollapseSeparators],
+  );
+
+  const emailOptions: EmailFilenameOptions = useMemo(
+    () => ({ ...transform, template: emailDownloadTemplate || DEFAULT_EMAIL_TEMPLATE }),
+    [transform, emailDownloadTemplate],
+  );
+  const attachmentOptions: EmailFilenameOptions = useMemo(
+    () => ({ ...transform, template: attachmentDownloadTemplate || DEFAULT_ATTACHMENT_TEMPLATE }),
+    [transform, attachmentDownloadTemplate],
+  );
+
   const emlPreview = useMemo(
-    () => emailExportFilename(sampleEmail, emailDownloadTemplate || DEFAULT_EMAIL_TEMPLATE),
-    [sampleEmail, emailDownloadTemplate],
+    () => emailExportFilename(sampleEmail, emailOptions),
+    [sampleEmail, emailOptions],
   );
   const attachmentPreview = useMemo(
-    () =>
-      attachmentDownloadFilename(
-        sampleEmail,
-        sampleAttachment,
-        attachmentDownloadTemplate || DEFAULT_ATTACHMENT_TEMPLATE,
-      ),
-    [sampleEmail, sampleAttachment, attachmentDownloadTemplate],
+    () => attachmentDownloadFilename(sampleEmail, sampleAttachment, attachmentOptions),
+    [sampleEmail, sampleAttachment, attachmentOptions],
   );
 
   return (
@@ -154,6 +179,7 @@ export function DownloadsSettings() {
         preview={emlPreview}
         onChange={(next) => updateSetting("emailDownloadTemplate", next)}
         resetLabel={t("reset")}
+        previewLabel={t("preview")}
         placeholder={DEFAULT_EMAIL_TEMPLATE}
       />
       <TemplateEditor
@@ -165,8 +191,38 @@ export function DownloadsSettings() {
         preview={attachmentPreview}
         onChange={(next) => updateSetting("attachmentDownloadTemplate", next)}
         resetLabel={t("reset")}
+        previewLabel={t("preview")}
         placeholder={DEFAULT_ATTACHMENT_TEMPLATE}
       />
+      <SettingItem label={t("spaces.label")} description={t("spaces.description")}>
+        <Select
+          value={filenameSpaceReplacement}
+          onChange={(value) => updateSetting("filenameSpaceReplacement", value as "keep" | "underscore" | "dash")}
+          options={[
+            { value: "keep", label: t("spaces.keep") },
+            { value: "underscore", label: t("spaces.underscore") },
+            { value: "dash", label: t("spaces.dash") },
+          ]}
+        />
+      </SettingItem>
+      <SettingItem label={t("lowercase.label")} description={t("lowercase.description")}>
+        <ToggleSwitch
+          checked={filenameLowercase}
+          onChange={(checked) => updateSetting("filenameLowercase", checked)}
+        />
+      </SettingItem>
+      <SettingItem label={t("strip_diacritics.label")} description={t("strip_diacritics.description")}>
+        <ToggleSwitch
+          checked={filenameStripDiacritics}
+          onChange={(checked) => updateSetting("filenameStripDiacritics", checked)}
+        />
+      </SettingItem>
+      <SettingItem label={t("collapse_separators.label")} description={t("collapse_separators.description")}>
+        <ToggleSwitch
+          checked={filenameCollapseSeparators}
+          onChange={(checked) => updateSetting("filenameCollapseSeparators", checked)}
+        />
+      </SettingItem>
     </SettingsSection>
   );
 }
diff --git a/hooks/use-email-drag.ts b/hooks/use-email-drag.ts
index 1e65d09b..5ad45977 100644
--- a/hooks/use-email-drag.ts
+++ b/hooks/use-email-drag.ts
@@ -1,6 +1,6 @@
 "use client";
 
-import { useCallback, useEffect, useRef, DragEvent } from "react";
+import { useCallback, useEffect, useMemo, useRef, DragEvent } from "react";
 import { Email } from "@/lib/jmap/types";
 import { IJMAPClient } from "@/lib/jmap/client-interface";
 import { useEmailStore } from "@/stores/email-store";
@@ -8,7 +8,7 @@ import { useAuthStore } from "@/stores/auth-store";
 import { useDragDropContext } from "@/contexts/drag-drop-context";
 import { useUIStore } from "@/stores/ui-store";
 import { isDragOutSupported } from "@/hooks/use-attachment-drag";
-import { emailExportFilename, DEFAULT_EMAIL_TEMPLATE } from "@/lib/download-filename";
+import { emailExportFilename, DEFAULT_EMAIL_TEMPLATE, type EmailFilenameOptions } from "@/lib/download-filename";
 import { useSettingsStore } from "@/stores/settings-store";
 
 interface UseEmailDragOptions {
@@ -71,7 +71,7 @@ function selectionKey(ids: string[]): string {
   return [...ids].sort().join(",");
 }
 
-async function buildEmailZip(client: IJMAPClient, emails: Email[], template: string): Promise<string | null> {
+async function buildEmailZip(client: IJMAPClient, emails: Email[], options: EmailFilenameOptions): Promise<string | null> {
   const eligible = emails.filter((em) => !!em.blobId);
   if (eligible.length === 0) return null;
   const { default: JSZip } = await import("jszip");
@@ -79,7 +79,7 @@ async function buildEmailZip(client: IJMAPClient, emails: Email[], template: str
   const used = new Set<string>();
   await Promise.all(
     eligible.map(async (em) => {
-      const base = emailExportFilename(em, template).replace(/\.eml$/, "");
+      const base = emailExportFilename(em, options).replace(/\.eml$/, "");
       let name = `${base}.eml`;
       while (used.has(name)) name = `${base} [${em.id.slice(0, 6)}].eml`;
       used.add(name);
@@ -95,7 +95,7 @@ async function buildEmailZip(client: IJMAPClient, emails: Email[], template: str
   return URL.createObjectURL(zipBlob);
 }
 
-function prefetchEmailBundle(client: IJMAPClient, emails: Email[], template: string): void {
+function prefetchEmailBundle(client: IJMAPClient, emails: Email[], options: EmailFilenameOptions): void {
   const key = selectionKey(emails.map((e) => e.id));
   if (currentBundle && currentBundle.key === key) return;
   if (currentBundle?.url) {
@@ -108,7 +108,7 @@ function prefetchEmailBundle(client: IJMAPClient, emails: Email[], template: str
     url: null,
     promise: null,
   };
-  entry.promise = buildEmailZip(client, emails, template)
+  entry.promise = buildEmailZip(client, emails, options)
     .then((url) => {
       if (url && currentBundle === entry) entry.url = url;
       return url;
@@ -130,7 +130,15 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
   const { startDrag, endDrag, isDragging, draggedEmails } = useDragDropContext();
   const isMobile = useUIStore((state) => state.isMobile);
   const client = useAuthStore((state) => state.client);
-  const emailTemplate = useSettingsStore((s) => s.emailDownloadTemplate) || DEFAULT_EMAIL_TEMPLATE;
+  const template = useSettingsStore((s) => s.emailDownloadTemplate) || DEFAULT_EMAIL_TEMPLATE;
+  const spaceReplacement = useSettingsStore((s) => s.filenameSpaceReplacement);
+  const lowercase = useSettingsStore((s) => s.filenameLowercase);
+  const stripDiacritics = useSettingsStore((s) => s.filenameStripDiacritics);
+  const collapseSeparators = useSettingsStore((s) => s.filenameCollapseSeparators);
+  const filenameOptions: EmailFilenameOptions = useMemo(
+    () => ({ template, spaceReplacement, lowercase, stripDiacritics, collapseSeparators }),
+    [template, spaceReplacement, lowercase, stripDiacritics, collapseSeparators],
+  );
 
   const dragOutEnabled = !isMobile && isDragOutSupported() && !!client;
   const singleBlobUrlRef = useRef<string | null>(null);
@@ -152,7 +160,7 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
   const prefetchSingle = useCallback(() => {
     if (!dragOutEnabled || !client || !email.blobId) return;
     if (singleBlobUrlRef.current || inFlightRef.current) return;
-    const name = emailExportFilename(email, emailTemplate);
+    const name = emailExportFilename(email, filenameOptions);
     inFlightRef.current = client
       .fetchBlobAsObjectUrl(email.blobId, name, "message/rfc822")
       .then((url) => {
@@ -163,7 +171,7 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
       .finally(() => {
         inFlightRef.current = null;
       });
-  }, [dragOutEnabled, client, email, emailTemplate]);
+  }, [dragOutEnabled, client, email, filenameOptions]);
 
   const handlePointerEnter = useCallback(() => {
     if (!dragOutEnabled || !client) return;
@@ -173,12 +181,12 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
       const selected = emails.filter((em) => selectedEmailIds.has(em.id));
       // Only worth bundling when at least one selected email has a blobId.
       if (selected.some((em) => em.blobId)) {
-        prefetchEmailBundle(client, selected, emailTemplate);
+        prefetchEmailBundle(client, selected, filenameOptions);
       }
     } else {
       prefetchSingle();
     }
-  }, [dragOutEnabled, client, selectedEmailIds, email.id, emails, prefetchSingle, emailTemplate]);
+  }, [dragOutEnabled, client, selectedEmailIds, email.id, emails, prefetchSingle, filenameOptions]);
 
   const handleDragStart = useCallback((e: DragEvent<HTMLDivElement>) => {
     // Determine which emails to drag:
@@ -205,7 +213,7 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
       if (emailsToDrag.length === 1 && emailsToDrag[0].blobId) {
         const url = singleBlobUrlRef.current;
         if (url) {
-          const name = emailExportFilename(emailsToDrag[0], emailTemplate);
+          const name = emailExportFilename(emailsToDrag[0], filenameOptions);
           // `DownloadURL` format: <mime>:<filename>:<url>. Chromium expects
           // the filename raw - URL-encoding it ends up literally on disk
           // (e.g. `%20` instead of a space). The sanitiser already removed
@@ -229,7 +237,7 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
           );
         } else {
           // Kick off the bundle build for the next attempt.
-          prefetchEmailBundle(client, emailsToDrag, emailTemplate);
+          prefetchEmailBundle(client, emailsToDrag, filenameOptions);
         }
       }
     }
@@ -244,7 +252,7 @@ export function useEmailDrag({ email, sourceMailboxId, threadEmails }: UseEmailD
     });
 
     startDrag(emailsToDrag, sourceMailboxId);
-  }, [email, selectedEmailIds, emails, sourceMailboxId, startDrag, threadEmails, dragOutEnabled, client, prefetchSingle, emailTemplate]);
+  }, [email, selectedEmailIds, emails, sourceMailboxId, startDrag, threadEmails, dragOutEnabled, client, prefetchSingle, filenameOptions]);
 
   const handleDragEnd = useCallback(() => {
     endDrag();
diff --git a/lib/download-filename.ts b/lib/download-filename.ts
index a99dda98..1306ca1a 100644
--- a/lib/download-filename.ts
+++ b/lib/download-filename.ts
@@ -7,6 +7,26 @@ import type { Email } from "@/lib/jmap/types";
 // non-ASCII scripts.
 const SAFE_CHARS = /[^\p{L}\p{N} _\-().,!@#&+=[\]{}']/gu;
 
+export type SpaceReplacement = "keep" | "underscore" | "dash";
+
+export interface FilenameTransformOptions {
+  spaceReplacement?: SpaceReplacement;
+  lowercase?: boolean;
+  stripDiacritics?: boolean;
+  collapseSeparators?: boolean;
+}
+
+export interface EmailFilenameOptions extends FilenameTransformOptions {
+  template?: string;
+}
+
+export const DEFAULT_TRANSFORM: Required<FilenameTransformOptions> = {
+  spaceReplacement: "keep",
+  lowercase: false,
+  stripDiacritics: false,
+  collapseSeparators: true,
+};
+
 export const DEFAULT_EMAIL_TEMPLATE = "{date} ({from}-{to}) {subject}";
 export const DEFAULT_ATTACHMENT_TEMPLATE = "{filename}";
 
@@ -43,6 +63,24 @@ function sanitizePart(input: string, maxLen = 80): string {
   return cleaned.slice(0, maxLen);
 }
 
+function applyTransforms(input: string, opts: FilenameTransformOptions): string {
+  let s = input;
+  if (opts.stripDiacritics) {
+    // NFD splits "ä" into "a" + U+0308 (combining diaeresis); stripping all
+    // combining marks then leaves plain ASCII letters. `ß` has no
+    // decomposition so it survives as-is.
+    s = s.normalize("NFD").replace(/\p{M}+/gu, "");
+  }
+  const repl = opts.spaceReplacement ?? "keep";
+  if (repl === "underscore") s = s.replace(/ +/g, "_");
+  else if (repl === "dash") s = s.replace(/ +/g, "-");
+  if (opts.collapseSeparators ?? true) {
+    s = s.replace(/_+/g, "_").replace(/-+/g, "-").replace(/ +/g, " ");
+  }
+  if (opts.lowercase) s = s.toLocaleLowerCase();
+  return s.replace(/^[._\- ]+|[._\- ]+$/g, "");
+}
+
 function pad2(n: number): string {
   return String(n).padStart(2, "0");
 }
@@ -120,43 +158,38 @@ export function attachmentVars(email: Email, attachment: AttachmentLike): Record
   };
 }
 
-// Render a template by substituting `{key}` occurrences. Each substituted
-// value is sanitized to safe ASCII filename characters; the rest of the
-// template (literal text) is sanitized as a whole at the end so the template
-// itself can't introduce path separators or control chars.
-export function renderTemplate(
-  template: string,
-  vars: Record<string, string>,
-  fallback: string,
-): string {
-  const rendered = template.replace(/\{(\w+)\}/g, (_, key: string) => {
+function renderRaw(template: string, vars: Record<string, string>): string {
+  return template.replace(/\{(\w+)\}/g, (_, key: string) => {
     const value = vars[key];
     if (value === undefined) return "";
     return sanitizePart(value);
   });
-  const cleaned = sanitizePart(rendered, 200);
-  return cleaned || fallback;
 }
 
 export function emailExportFilename(
   email: Email,
-  template: string = DEFAULT_EMAIL_TEMPLATE,
+  options: EmailFilenameOptions | string = {},
 ): string {
-  const stem = renderTemplate(template, emailVars(email), "email");
+  const opts = typeof options === "string" ? { template: options } : options;
+  const template = opts.template ?? DEFAULT_EMAIL_TEMPLATE;
+  const rendered = renderRaw(template, emailVars(email));
+  const cleaned = sanitizePart(rendered, 200);
+  const transformed = applyTransforms(cleaned, opts);
+  const stem = transformed.slice(0, 200) || "email";
   return `${stem}.eml`;
 }
 
 export function attachmentDownloadFilename(
   email: Email | null | undefined,
   attachment: AttachmentLike,
-  template: string = DEFAULT_ATTACHMENT_TEMPLATE,
+  options: EmailFilenameOptions | string = {},
 ): string {
-  // No email context (rare - e.g. compose attachments) means we can only
-  // honour the {filename}/{name}/{ext} subset, so fall back to the raw name
-  // when the template needs email data and we don't have it.
+  const opts = typeof options === "string" ? { template: options } : options;
+  const template = opts.template ?? DEFAULT_ATTACHMENT_TEMPLATE;
   if (!email) {
     const filename = (attachment.name || "attachment").trim();
-    return sanitizePart(filename, 200) || "attachment";
+    const cleaned = sanitizePart(filename, 200) || "attachment";
+    return applyTransforms(cleaned, opts) || cleaned;
   }
   const vars = attachmentVars(email, attachment);
   const rendered = template.replace(/\{(\w+)\}/g, (_, key: string) => {
@@ -166,12 +199,16 @@ export function attachmentDownloadFilename(
     // sanitiser (it strips trailing dots otherwise).
     return key === "filename" ? value.replace(SAFE_CHARS, "_") : sanitizePart(value);
   });
-  // Preserve the original extension when the template doesn't reference it.
   const templateMentionsExt = /\{(ext|filename)\}/.test(template);
   const cleaned = sanitizePart(rendered, 200) || "attachment";
-  if (templateMentionsExt) return cleaned;
+  if (templateMentionsExt) {
+    return applyTransforms(cleaned, opts) || cleaned;
+  }
+  const transformedStem = applyTransforms(cleaned, opts) || cleaned;
   const ext = vars.ext;
-  return ext ? `${cleaned}.${ext}` : cleaned;
+  if (!ext) return transformedStem;
+  const transformedExt = opts.lowercase ? ext.toLocaleLowerCase() : ext;
+  return `${transformedStem}.${transformedExt}`;
 }
 
 // Build a synthetic email for previewing templates in the settings UI.
@@ -189,7 +226,7 @@ export function buildSampleEmail(): Email {
     from: [{ name: "Alice Sender", email: "alice@example.com" }],
     to: [{ name: "Bob Recipient", email: "bob@example.com" }],
     cc: [],
-    subject: "Quarterly report draft",
+    subject: "Benachrichtigung von Ihrem Gerät",
     preview: "",
     hasAttachment: true,
     blobId: "sample-blob",
diff --git a/locales/en/common.json b/locales/en/common.json
index e347944c..02143e5a 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -1503,6 +1503,7 @@
       "title": "Downloads",
       "description": "Customize how downloaded emails and attachments are named.",
       "reset": "Restore default",
+      "preview": "Preview:",
       "email_template": {
         "label": "Email (.eml) filename",
         "description": "Template used when you export an email or drag one out to the file system. The .eml extension is added automatically."
@@ -1510,6 +1511,25 @@
       "attachment_template": {
         "label": "Attachment filename",
         "description": "Template used when downloading or dragging out an attachment. If you omit {filename} and {ext}, the original extension is preserved."
+      },
+      "spaces": {
+        "label": "Spaces",
+        "description": "Replace spaces in the resulting filename with another character.",
+        "keep": "Keep spaces",
+        "underscore": "Replace with _",
+        "dash": "Replace with -"
+      },
+      "lowercase": {
+        "label": "Lowercase",
+        "description": "Force the entire filename to lowercase."
+      },
+      "strip_diacritics": {
+        "label": "Strip diacritics",
+        "description": "Convert accented letters to their ASCII equivalents (ä → a, é → e). Useful for tools that mangle Unicode filenames."
+      },
+      "collapse_separators": {
+        "label": "Collapse repeated separators",
+        "description": "Collapse runs of spaces, underscores, or dashes to a single character."
       }
     },
     "filters": {
diff --git a/stores/settings-store.ts b/stores/settings-store.ts
index 4df42fe7..a9c95a87 100644
--- a/stores/settings-store.ts
+++ b/stores/settings-store.ts
@@ -242,6 +242,10 @@ interface SettingsState {
   // Downloads
   emailDownloadTemplate: string;
   attachmentDownloadTemplate: string;
+  filenameSpaceReplacement: 'keep' | 'underscore' | 'dash';
+  filenameLowercase: boolean;
+  filenameStripDiacritics: boolean;
+  filenameCollapseSeparators: boolean;
 
   // Advanced
   debugMode: boolean;
@@ -431,6 +435,10 @@ const DEFAULT_SETTINGS = {
   // Downloads
   emailDownloadTemplate: '{date} ({from}-{to}) {subject}',
   attachmentDownloadTemplate: '{filename}',
+  filenameSpaceReplacement: 'keep' as 'keep' | 'underscore' | 'dash',
+  filenameLowercase: false,
+  filenameStripDiacritics: false,
+  filenameCollapseSeparators: true,
 
   // Advanced
   debugMode: false,