diff --git a/core/lib/presentation/utils/html_transformer/dom/normalize_line_height_in_style_transformer.dart b/core/lib/presentation/utils/html_transformer/dom/normalize_line_height_in_style_transformer.dart
index cef2e672f..53eccd7c8 100644
--- a/core/lib/presentation/utils/html_transformer/dom/normalize_line_height_in_style_transformer.dart
+++ b/core/lib/presentation/utils/html_transformer/dom/normalize_line_height_in_style_transformer.dart
@@ -8,6 +8,12 @@ class NormalizeLineHeightInStyleTransformer extends DomTransformer {
 
   static const _removableLineHeights = ['1px', '100%'];
   static final _multipleSpacesRegex = RegExp(r' {2,}');
+  static final _lineHeightPattern = RegExp(
+    r'line-height\s*:\s*(?:' +
+        _removableLineHeights.map(RegExp.escape).join('|') +
+        r')\s*;?',
+    caseSensitive: false,
+  );
 
   @override
   Future<void> process({
@@ -16,11 +22,7 @@ class NormalizeLineHeightInStyleTransformer extends DomTransformer {
     Map<String, String>? mapUrlDownloadCID,
   }) async {
     try {
-      final alternation = _removableLineHeights.map(RegExp.escape).join('|');
-      final pattern = RegExp(
-        r'line-height\s*:\s*(?:' + alternation + r')\s*;?',
-        caseSensitive: false,
-      );
+      
 
       final elements = document.querySelectorAll('[style*="line-height"]');
 
@@ -28,7 +30,7 @@ class NormalizeLineHeightInStyleTransformer extends DomTransformer {
         final originalStyle = element.attributes['style'];
         if (originalStyle == null) continue;
 
-        var updatedStyle = originalStyle.replaceAll(pattern, '').trim();
+        var updatedStyle = originalStyle.replaceAll(_lineHeightPattern, '').trim();
 
         // Remove extra spaces (>=2 spaces → 1 space)
         updatedStyle = updatedStyle.replaceAll(_multipleSpacesRegex, ' ');
diff --git a/core/lib/utils/html/html_utils.dart b/core/lib/utils/html/html_utils.dart
index baba7a2a1..794f5fb9c 100644
--- a/core/lib/utils/html/html_utils.dart
+++ b/core/lib/utils/html/html_utils.dart
@@ -34,6 +34,10 @@ class HtmlUtils {
     multiLine: true,
   );
   static final _protocolRegex = RegExp(r'^(?:https?|ftp|mailto|file)');
+  static final _tagRemovalRegex = RegExp(
+    '</?(?:${validTags.map(RegExp.escape).join('|')})(?:\\s+[^>]*)?>',
+    caseSensitive: false,
+  );
 
   static const removeLineHeight1px = (
     script: '''
@@ -861,12 +865,7 @@ class HtmlUtils {
     } while (decoded != cleaned && iterations < maxIterations);
 
     // Delete all remaining HTML tags → replace tag with space to avoid text sticking
-    final String tagsPipe = validTags.map(RegExp.escape).join('|');
-    final tagRegex = RegExp(
-      '</?(?:$tagsPipe)(?:\\s+[^>]*)?>',
-      caseSensitive: false,
-    );
-    cleaned = cleaned.replaceAll(tagRegex, ' ');
+    cleaned = cleaned.replaceAll(_tagRemovalRegex, ' ');
 
     // Normalize whitespace
     cleaned = cleaned.replaceAll(_whitespaceNormalizationRegex, ' ').trim();
diff --git a/core/test/utils/string_convert_test.dart b/core/test/utils/string_convert_test.dart
index d3dde6e70..fba8ee1e6 100644
--- a/core/test/utils/string_convert_test.dart
+++ b/core/test/utils/string_convert_test.dart
@@ -815,6 +815,32 @@ void main() {
         ]),
       );
     });
+    test('Does not corrupt plain text that looks like base64', () {
+       // "useruser" is 8 chars (multiple of 4) and fits the base64 regex.
+      // base64.decode("useruser") produces random bytes.
+      const input = 'useruser';
+      final result = StringConvert.extractNamedAddresses(input);
+      expect(result.first.address, equals('useruser'));
+    });
+    test('Handles brackets with no name', () {
+      const input = '<only-email@example.com>';
+      final result = StringConvert.extractNamedAddresses(input);
+      expect(result.first.name, isEmpty);
+      expect(result.first.address, equals('only-email@example.com'));
+    });
+    test('Handles names containing commas', () {
+      const input =
+          '"Doe, John" <john@example.com>, "Smith, Jane" <jane@example.com>';
+      final result = StringConvert.extractNamedAddresses(input);
+      expect(result[0].name, equals('Doe, John'));
+      expect(result[1].name, equals('Smith, Jane'));
+    });
+    test('Handles malformed input gracefully', () {
+      const input = '"Unclosed Quote <email@example.com>';
+      final result = StringConvert.extractNamedAddresses(input);
+      // Ensure it doesn't crash and returns at least the email
+      expect(result, isNotEmpty);
+    });
   });
 
   group('StringConvert.convertHtmlContentToTextContent', () {