diff --git a/lib/Controller/AccountsController.php b/lib/Controller/AccountsController.php
index bc1d6b3567..4eaf204fdf 100644
--- a/lib/Controller/AccountsController.php
+++ b/lib/Controller/AccountsController.php
@@ -216,6 +216,7 @@ public function update(int $id,
 	 * @param int|null $archiveMailboxId
 	 * @param int|null $snoozeMailboxId
 	 * @param bool|null $signatureAboveQuote
+	 * @param bool|null $signatureSeparator
 	 * @param bool|null $classificationEnabled
 	 *
 	 * @return JSONResponse
@@ -233,6 +234,7 @@ public function patchAccount(int $id,
 		?int $archiveMailboxId = null,
 		?int $snoozeMailboxId = null,
 		?bool $signatureAboveQuote = null,
+		?bool $signatureSeparator = null,
 		?int $trashRetentionDays = null,
 		?int $junkMailboxId = null,
 		?bool $searchBody = null,
@@ -276,6 +278,9 @@ public function patchAccount(int $id,
 		if ($signatureAboveQuote !== null) {
 			$dbAccount->setSignatureAboveQuote($signatureAboveQuote);
 		}
+		if ($signatureSeparator !== null) {
+			$dbAccount->setSignatureSeparator($signatureSeparator);
+		}
 		if ($trashRetentionDays !== null) {
 			// Passing 0 (or lower) disables retention
 			$dbAccount->setTrashRetentionDays($trashRetentionDays <= 0 ? null : $trashRetentionDays);
diff --git a/lib/Db/MailAccount.php b/lib/Db/MailAccount.php
index f3e8b900cb..60e60fffad 100644
--- a/lib/Db/MailAccount.php
+++ b/lib/Db/MailAccount.php
@@ -79,6 +79,8 @@
  * @method void setSievePassword(?string $sievePassword)
  * @method bool|null isSignatureAboveQuote()
  * @method void setSignatureAboveQuote(bool $signatureAboveQuote)
+ * @method bool|null isSignatureSeparator()
+ * @method void setSignatureSeparator(bool $signatureSeparator)
  * @method string getAuthMethod()
  * @method void setAuthMethod(string $method)
  * @method int getSignatureMode()
@@ -165,6 +167,8 @@ class MailAccount extends Entity {
 	protected $sievePassword;
 	/** @var bool */
 	protected $signatureAboveQuote = false;
+	/** @var bool */
+	protected $signatureSeparator = true;
 
 	/** @var int|null */
 	protected $provisioningId;
@@ -245,6 +249,9 @@ public function __construct(array $params = []) {
 		if (isset($params['signatureAboveQuote'])) {
 			$this->setSignatureAboveQuote($params['signatureAboveQuote']);
 		}
+		if (isset($params['signatureSeparator'])) {
+			$this->setSignatureSeparator($params['signatureSeparator']);
+		}
 		if (isset($params['trashRetentionDays'])) {
 			$this->setTrashRetentionDays($params['trashRetentionDays']);
 		}
@@ -276,6 +283,7 @@ public function __construct(array $params = []) {
 		$this->addType('sieveEnabled', 'boolean');
 		$this->addType('sievePort', 'integer');
 		$this->addType('signatureAboveQuote', 'boolean');
+		$this->addType('signatureSeparator', 'boolean');
 		$this->addType('signatureMode', 'integer');
 		$this->addType('smimeCertificateId', 'integer');
 		$this->addType('quotaPercentage', 'integer');
@@ -327,6 +335,7 @@ public function toJson() {
 			'snoozeMailboxId' => $this->getSnoozeMailboxId(),
 			'sieveEnabled' => ($this->isSieveEnabled() === true),
 			'signatureAboveQuote' => ($this->isSignatureAboveQuote() === true),
+			'signatureSeparator' => ($this->isSignatureSeparator() !== false),
 			'signatureMode' => $this->getSignatureMode(),
 			'smimeCertificateId' => $this->getSmimeCertificateId(),
 			'quotaPercentage' => $this->getQuotaPercentage(),
diff --git a/lib/Migration/Version5009Date20260617000000.php b/lib/Migration/Version5009Date20260617000000.php
new file mode 100644
index 0000000000..6f14b251e2
--- /dev/null
+++ b/lib/Migration/Version5009Date20260617000000.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/**
+ * @psalm-api
+ */
+class Version5009Date20260617000000 extends SimpleMigrationStep {
+	/**
+	 * @param IOutput $output
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param array $options
+	 *
+	 * @return ISchemaWrapper
+	 */
+	#[\Override]
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options) {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		$accountsTable = $schema->getTable('mail_accounts');
+
+		if (!$accountsTable->hasColumn('signature_separator')) {
+			$accountsTable->addColumn('signature_separator', Types::BOOLEAN, [
+				'notnull' => false,
+				'default' => true,
+			]);
+		}
+
+		return $schema;
+	}
+}
diff --git a/lib/UserMigration/MailAccountMigrator.php b/lib/UserMigration/MailAccountMigrator.php
index 424028f67e..d0571129c4 100644
--- a/lib/UserMigration/MailAccountMigrator.php
+++ b/lib/UserMigration/MailAccountMigrator.php
@@ -147,6 +147,7 @@ public function import(IUser $user, IImportSource $importSource, OutputInterface
 			$newAccount->setSearchBody($accountData['searchBody'] ?? false);
 			$newAccount->setClassificationEnabled($accountData['classificationEnabled'] ?? false);
 			$newAccount->setSignatureAboveQuote($accountData['signatureAboveQuote'] ?? false);
+			$newAccount->setSignatureSeparator($accountData['signatureSeparator'] ?? true);
 			$newAccount->setPersonalNamespace($accountData['personalNamespace'] ?? null);
 			if (isset($accountData['inboundPassword'])) {
 				$newAccount->setInboundPassword($this->crypto->encrypt($accountData['inboundPassword']));
diff --git a/src/ckeditor/signature/InsertSignatureCommand.js b/src/ckeditor/signature/InsertSignatureCommand.js
index 0eeab5bb21..210bca4697 100644
--- a/src/ckeditor/signature/InsertSignatureCommand.js
+++ b/src/ckeditor/signature/InsertSignatureCommand.js
@@ -34,8 +34,9 @@ export default class InsertSignatureCommand extends Command {
 	 * @param {module:engine/model/writer~Writer} writer instance
 	 * @param {string} signature text
 	 * @param {boolean} signatureAboveQuote signature position: above/below the quoted text
+	 * @param {boolean} signatureSeparator whether to prepend the "-- " separator above the signature
 	 */
-	insertSignatureElement(editor, writer, signature, signatureAboveQuote) {
+	insertSignatureElement(editor, writer, signature, signatureAboveQuote, signatureSeparator) {
 		// Skip empty signature
 		if (signature.length === 0) {
 			return
@@ -55,8 +56,10 @@ export default class InsertSignatureCommand extends Command {
 		const modelFragment = editor.data.toModel(viewFragment)
 
 		const signatureElement = writer.createElement('signature')
-		writer.append(writer.createText('-- '), signatureElement)
-		writer.append(writer.createElement('paragraph'), signatureElement)
+		if (signatureSeparator !== false) {
+			writer.append(writer.createText('-- '), signatureElement)
+			writer.append(writer.createElement('paragraph'), signatureElement)
+		}
 		writer.append(modelFragment, signatureElement)
 		if (signatureAboveQuote) {
 			writer.append(writer.createElement('paragraph'), signatureElement)
@@ -122,8 +125,9 @@ export default class InsertSignatureCommand extends Command {
 	 * @param {string} trigger TRIGGER_CHANGE_ALIAS or TRIGGER_EDITOR_READY
 	 * @param {string} signature text
 	 * @param {boolean} signatureAboveQuote signature position: above/below the quoted text
+	 * @param {boolean} signatureSeparator whether to prepend the "-- " separator above the signature
 	 */
-	execute(trigger, signature, signatureAboveQuote) {
+	execute(trigger, signature, signatureAboveQuote, signatureSeparator) {
 		this.editor.model.change((writer) => {
 			/**
 			 * TRIGGER_CHANGE_ALIAS:
@@ -139,11 +143,11 @@ export default class InsertSignatureCommand extends Command {
 
 			if (trigger === TRIGGER_CHANGE_ALIAS) {
 				this.removeSignatureElement(this.editor, writer)
-				this.insertSignatureElement(this.editor, writer, signature, signatureAboveQuote)
+				this.insertSignatureElement(this.editor, writer, signature, signatureAboveQuote, signatureSeparator)
 			}
 
 			if (trigger === TRIGGER_EDITOR_READY && !this.hasSignatureElement(this.editor)) {
-				this.insertSignatureElement(this.editor, writer, signature, signatureAboveQuote)
+				this.insertSignatureElement(this.editor, writer, signature, signatureAboveQuote, signatureSeparator)
 			}
 		})
 	}
diff --git a/src/components/Composer.vue b/src/components/Composer.vue
index e8c217aeb1..8a5d31c221 100644
--- a/src/components/Composer.vue
+++ b/src/components/Composer.vue
@@ -798,6 +798,7 @@ export default {
 					name: account.name,
 					emailAddress: account.emailAddress,
 					signatureAboveQuote: account.signatureAboveQuote,
+					signatureSeparator: account.signatureSeparator,
 					smimeCertificateId: account.smimeCertificateId,
 					selectable: account.connectionStatus,
 				},
@@ -811,6 +812,7 @@ export default {
 						name: alias.name,
 						emailAddress: alias.alias,
 						signatureAboveQuote: account.signatureAboveQuote,
+						signatureSeparator: account.signatureSeparator,
 						smimeCertificateId: alias.smimeCertificateId,
 						selectable: account.connectionStatus,
 					}
@@ -1307,6 +1309,7 @@ export default {
 				trigger,
 				toHtml(detect(this.selectedAlias.signature)).value,
 				this.selectedAlias.signatureAboveQuote,
+				this.selectedAlias.signatureSeparator,
 			)
 
 			this.changeSignature = false
diff --git a/src/components/SignatureSettings.vue b/src/components/SignatureSettings.vue
index e5bdc18d27..42299c9ee2 100644
--- a/src/components/SignatureSettings.vue
+++ b/src/components/SignatureSettings.vue
@@ -15,6 +15,16 @@
 				{{ t("mail", "Place signature above quoted text") }}
 			</label>
 		</div>
+		<div>
+			<input
+				id="signature-separator-toggle"
+				v-model="signatureSeparator"
+				type="checkbox"
+				class="checkbox">
+			<label for="signature-separator-toggle">
+				{{ t("mail", "Add a separator line (--) above the signature") }}
+			</label>
+		</div>
 		<NcSelect
 			v-if="identities.length > 1"
 			:allow-empty="false"
@@ -93,6 +103,7 @@ export default {
 			identity: null,
 			signature: '',
 			signatureAboveQuote: this.account.signatureAboveQuote,
+			signatureSeparator: this.account.signatureSeparator,
 		}
 	},
 
@@ -136,6 +147,20 @@ export default {
 				this.signatureAboveQuote = oldVal
 			}
 		},
+		async signatureSeparator(val, oldVal) {
+			try {
+				await this.mainStore.patchAccount({
+					account: this.account,
+					data: {
+						signatureSeparator: val,
+					},
+				})
+				logger.debug('signature separator updated to ' + val)
+			} catch (e) {
+				logger.error('could not update signature separator', { e })
+				this.signatureSeparator = oldVal
+			}
+		},
 	},
 
 	beforeMount() {
diff --git a/src/store/mainStore.js b/src/store/mainStore.js
index dba4d9a882..9cf9d5b481 100644
--- a/src/store/mainStore.js
+++ b/src/store/mainStore.js
@@ -31,6 +31,7 @@ export default defineStore('main', {
 					name: '',
 					showSubscribedOnly: false,
 					signatureAboveQuote: false,
+					signatureSeparator: true,
 				},
 			},
 			accountList: [UNIFIED_ACCOUNT_ID],
diff --git a/src/tests/unit/components/SignaturePlugin.spec.js b/src/tests/unit/components/SignaturePlugin.spec.js
index 34402dee2a..36ab9f14b8 100644
--- a/src/tests/unit/components/SignaturePlugin.spec.js
+++ b/src/tests/unit/components/SignaturePlugin.spec.js
@@ -53,6 +53,27 @@ describe('SignaturePlugin', () => {
 			expect(editor.getData()).toEqual(text)
 		})
 
+		it('Add signature without separator', async () => {
+			const text = '<p>bonjour bonjour</p>'
+			const expected = '<p>bonjour bonjour</p><div class="signature"><p>Jane Doe</p></div>'
+
+			const editor = await VirtualTestEditor.create({
+				licenseKey: 'GPL',
+				initialData: text,
+				plugins: [Paragraph, SignaturePlugin],
+			})
+
+			editor.execute(
+				'insertSignature',
+				TRIGGER_EDITOR_READY,
+				'<p>Jane Doe</p>',
+				false,
+				false,
+			)
+
+			expect(editor.getData()).toEqual(expected)
+		})
+
 		it('Add signature to content above quote', async () => {
 			const text = '<p>bonjour bonjour</p><div class="quote">"John Doe" john.doe@localhost - January 1, 1970 1:00 AM <blockquote><p>bonjour bonjour</p></blockquote></div>'
 			const expected = '<p>bonjour bonjour</p><div class="signature">--&nbsp;<p>&nbsp;</p><p>Jane Doe</p><p>&nbsp;</p></div><div class="quote"><p>"John Doe" john.doe@localhost - January 1, 1970 1:00 AM</p><p>bonjour bonjour</p></div>'
diff --git a/tests/Integration/Db/MailAccountTest.php b/tests/Integration/Db/MailAccountTest.php
index 0d2efc5bae..fc5f2747b4 100644
--- a/tests/Integration/Db/MailAccountTest.php
+++ b/tests/Integration/Db/MailAccountTest.php
@@ -62,6 +62,7 @@ public function testToAPI() {
 			'archiveMailboxId' => null,
 			'sieveEnabled' => false,
 			'signatureAboveQuote' => false,
+			'signatureSeparator' => true,
 			'signatureMode' => null,
 			'smimeCertificateId' => null,
 			'quotaPercentage' => 10,
@@ -103,6 +104,7 @@ public function testMailAccountConstruct() {
 			'archiveMailboxId' => null,
 			'sieveEnabled' => false,
 			'signatureAboveQuote' => false,
+			'signatureSeparator' => true,
 			'signatureMode' => null,
 			'smimeCertificateId' => null,
 			'quotaPercentage' => null,