diff --git a/html-editor-lib.pl b/html-editor-lib.pl
index 94c85cf5d..09736bcec 100644
--- a/html-editor-lib.pl
+++ b/html-editor-lib.pl
@@ -242,6 +242,9 @@ my $iframe_styles =
 $iframe_styles =~ s/\n/ /g;
 my $navigation_type = $ENV{'HTTP_X_NAVIGATION_TYPE'};
 $navigation_type ||= 'reload';
+
+# Key for preserving unsaved editor content across page reloads
+my $storage_key = $opts->{'storage'} || 'quill=last-message';
 my $html_editor_init_script =
 <<EOF;
 <script type="text/javascript">
@@ -263,6 +266,60 @@ my $html_editor_init_script =
     qf.whitelist = ["monospace"],
     Quill.register(qf, true);
 
+    // Register signature class attributor, so signature blocks keep their
+    // marking class across editor round trips, e.g. when editing a draft
+    const qp = Quill.import('parchment');
+    Quill.register(new qp.Attributor.Class('signature', 'x-signature',
+        { scope: qp.Scope.BLOCK }), true);
+
+    // Convert the signature container into per-block marking classes,
+    // which the editor preserves via the registered signature attributor.
+    // Block children are marked directly, while runs of inline content,
+    // like plain text with line breaks, become marked paragraphs
+    const signature_marks = function(html) {
+        if (!html || html.indexOf('x-signature') < 0) {
+            return html;
+        }
+        const doc = document.createElement('div'),
+              blocks = ['P', 'DIV', 'UL', 'OL', 'TABLE',
+                        'BLOCKQUOTE', 'PRE', 'H1', 'H2', 'H3', 'H4', 'H5', 'H6'];
+        doc.innerHTML = html;
+        doc.querySelectorAll('div.x-signature').forEach(function(sig) {
+            const frag = document.createDocumentFragment();
+            let run = [];
+            const run_empty = function() {
+                return !run.some(function(n) {
+                    return n.nodeType === 1 || (n.textContent || '').trim();
+                });
+            };
+            const flush = function() {
+                if (run.length && !run_empty()) {
+                    const p = document.createElement('p');
+                    p.className = 'x-signature-mark';
+                    run.forEach(function(n) { p.appendChild(n); });
+                    frag.appendChild(p);
+                }
+                run = [];
+            };
+            Array.from(sig.childNodes).forEach(function(node) {
+                if (node.nodeType === 1 && blocks.includes(node.tagName)) {
+                    // Mark block level parts of the signature directly
+                    flush();
+                    node.classList.add('x-signature-mark');
+                    frag.appendChild(node);
+                } else if (node.nodeType === 1 && node.tagName === 'BR') {
+                    // Line break ends the current inline line
+                    flush();
+                } else {
+                    run.push(node);
+                }
+            });
+            flush();
+            sig.replaceWith(frag);
+        });
+        return doc.innerHTML;
+    };
+
     const editor = new Quill('.ql-container', {
         modules: {
             syntax: typeof hljs === 'object',
@@ -332,7 +389,7 @@ my $html_editor_init_script =
     editor.on('text-change', function() {
         // This should most probably go to onSubmit event
         targ.value = editor.root.innerHTML + "<br>";
-        sessionStorage.setItem('$module_name/quill=last-message', editor.root.innerHTML);
+        sessionStorage.setItem('$module_name/$storage_key', editor.root.innerHTML);
         let extraValue = String(),
             sync = JSON.parse('@{[&convert_to_json($opts->{'textarea'}->{'sync'}->{'data'})]}'),
             position = '@{[$opts->{'textarea'}->{'sync'}->{'position'}]}',
@@ -386,7 +443,7 @@ my $html_editor_init_script =
       restore_message = false;
     }
     if (restore_message) {
-        const quill_last_message = sessionStorage.getItem('$module_name/quill=last-message');
+        const quill_last_message = sessionStorage.getItem('$module_name/$storage_key');
         if (quill_last_message) {
             editor.pasteHTML(quill_last_message);
             return;
@@ -394,8 +451,8 @@ my $html_editor_init_script =
     }
 
     // Update editor on initial load
-    editor.pasteHTML(targ.value);
-    sessionStorage.setItem('$module_name/quill=last-message', editor.root.innerHTML);
+    editor.pasteHTML(signature_marks(targ.value));
+    sessionStorage.setItem('$module_name/$storage_key', editor.root.innerHTML);
   }
   @{[$opts->{'load'} ? "fn_${module_name}_html_editor_init()" : '']}
 </script>
@@ -506,13 +563,13 @@ if ($document_styles_string) {
                 }
             }
         }
-    # Fill tags with our inline styles
+    # Fill tags with our inline styles, preserving existing tag attributes
     my (@document_styles_tag_names) = $styled_html_email =~ /<(?!style)(?!script)(?!s)(\w+)\s*.*?>/migx;
     foreach my $tag_name (&unique(@document_styles_tag_names)) {
         my (%document_styles_tag_names) = $document_styles_string =~ /(\Q$tag_name\E)\s*\{\s*([^}]*?)\s*\}/migx;
         foreach my $tag (keys %document_styles_tag_names) {
             my $tag_style = &$style_format($document_styles_tag_names{$tag});
-            $styled_html_email =~ s/(<$tag)(?![^>]+style).*?>/$1 style="$tag_style">/mig;
+            $styled_html_email =~ s/(<$tag\b)(?![^>]+style)([^>]*)>/$1$2 style="$tag_style">/mig;
             }
         }
     }
diff --git a/mailboxes/folders-lib.pl b/mailboxes/folders-lib.pl
index f897771e0..fa7f12c64 100755
--- a/mailboxes/folders-lib.pl
+++ b/mailboxes/folders-lib.pl
@@ -3285,6 +3285,14 @@ foreach my $a (@$attach) {
 return @rv;
 }
 
+# signature_is_html(sig)
+# Returns 1 if the given signature contains HTML markup
+sub signature_is_html
+{
+local ($sig) = @_;
+return 0 if (!$sig);
+return $sig =~ /<\/?(?:a|b|i|u|s|p|em|img|br|hr|div|span|font|code|pre|sub|sup|small|big|strong|strike|blockquote|table|tbody|thead|tr|td|th|ul|ol|li|h[1-6]|style)\b[^>]*>/i ? 1 : 0;
+}
 # quoted_message(&mail, quote-mode, sig, 0=any,1=text,2=html, sig-at-top?)
 # Returns the quoted text, html-flag and body attachment
 sub quoted_message
@@ -3315,20 +3323,22 @@ local $qm = %userconfig ? $userconfig{'html_quote'} : $config{'html_quote'};
 if (($cfg->{'html_edit'} == 2 ||
      $cfg->{'html_edit'} == 1 && $htmlbody) &&
      $bodymode != 1) {
-	# Create quoted body HTML
+	# Create quoted body HTML, with the signature wrapped in a container
+	# with a known class so that it can be styled later if needed
+	$sig =~ s/\n/<br>\n/g if (!&signature_is_html($sig));
+	$sig = "<div class=\"x-signature\">$sig</div>" if ($sig);
 	if ($htmlbody) {
 		$body = $htmlbody;
-		$sig =~ s/\n/<br>\n/g;
 		if ($qu && $qm == 0) {
 			# Quoted HTML as cite
 			$quote = &html_escape($writer)."\n".
 				 "<blockquote type=cite>\n".
 				 &safe_html($htmlbody->{'data'}).
 				 "</blockquote>";
-			if ($sigtop) {
+			if ($sig && $sigtop) {
 				$quote = $sig."<br>\n".$quote;
 				}
-			else {
+			elsif ($sig) {
 				$quote = $quote.$sig."<br>\n";
 				}
 			}
@@ -3341,10 +3351,10 @@ if (($cfg->{'html_edit'} == 2 ||
 		else {
 			# Un-quoted HTML
 			$quote = &safe_html($htmlbody->{'data'});
-			if ($sigtop) {
+			if ($sig && $sigtop) {
 				$quote = $sig."<br>\n".$quote;
 				}
-			else {
+			elsif ($sig) {
 				$quote = $quote.$sig."<br>\n";
 				}
 			}
@@ -3360,10 +3370,10 @@ if (($cfg->{'html_edit'} == 2 ||
 				 "<blockquote type=cite>\n".
 				 "<pre>$pd</pre>".
 				 "</blockquote>";
-			if ($sigtop) {
+			if ($sig && $sigtop) {
 				$quote = $sig."<br>\n".$quote;
 				}
-			else {
+			elsif ($sig) {
 				$quote = $quote.$sig."<br>\n";
 				}
 			}
@@ -3376,10 +3386,10 @@ if (($cfg->{'html_edit'} == 2 ||
 		else {
 			# Un-quoted plain text as HTML
 			$quote = "<pre>$pd</pre>";
-			if ($sigtop) {
+			if ($sig && $sigtop) {
 				$quote = $sig."<br>\n".$quote;
 				}
-			else {
+			elsif ($sig) {
 				$quote = $quote.$sig."<br>\n";
 				}
 			}
@@ -3388,6 +3398,7 @@ if (($cfg->{'html_edit'} == 2 ||
 	}
 else {
 	# Create quoted body text
+	$sig = &html_to_text($sig) if (&signature_is_html($sig));
 	if ($plainbody) {
 		$body = $plainbody;
 		$quote = $plainbody->{'data'};
diff --git a/mailboxes/reply_mail.cgi b/mailboxes/reply_mail.cgi
index d4e02a6a3..465ab24ca 100755
--- a/mailboxes/reply_mail.cgi
+++ b/mailboxes/reply_mail.cgi
@@ -21,10 +21,12 @@ if ($in{'new'}) {
 		}
 	$sig = &get_signature($in{'user'});
 	if ($html_edit && $sig) {
-		$sig =~ s/\n/<br>\n/g;
-		$quote = "<html><body>$sig</body></html>";
+		$sig =~ s/\n/<br>\n/g if (!&signature_is_html($sig));
+		$quote = "<html><body><div class=\"x-signature\">$sig</div>".
+			 "</body></html>";
 		}
 	else {
+		$sig = &html_to_text($sig) if (&signature_is_html($sig));
 		$quote = "\n\n$sig" if ($sig);
 		}
 	$to = $in{'to'};
@@ -313,8 +315,9 @@ else {
 	$subject = "Fwd: ".$subject if ($subject !~ /^Fwd:/i &&
 					($in{'forward'} || @mailforward));
 
-	# Construct the initial mail text
-	$sig = &get_signature($in{'user'});
+	# Construct the initial mail text, without adding a signature when
+	# editing an existing draft which already contains one
+	$sig = &get_signature($in{'user'}) if (!$in{'enew'});
 	($quote, $html_edit, $body) = &quoted_message($mail, $qu, $sig);
 	# Load images using server in replies
 	$quote = &disable_html_images($quote, 3);
@@ -476,10 +479,11 @@ if ($html_edit) {
 	        after =>
 	           { editor => $iframe_quote }
 	      });
-	$sig =~ s/\n/<br>/g,
-	$sig =~ s/^\s+//g,
-	$sig = "<br><br>$sig<br><br>"
-		if ($sig);
+	if ($sig) {
+		$sig =~ s/\n/<br>/g if (!&signature_is_html($sig));
+		$sig =~ s/^\s+//g;
+		$sig = "<br><br><div class=\"x-signature\">$sig</div><br><br>";
+		}
 	print &ui_table_row(undef,
 		&ui_textarea("body", $sig, 12, 80, undef, 0,
 		             "style='display: none' id=body data-html-mode='$config{'html_edit_mode'}'").
@@ -487,6 +491,7 @@ if ($html_edit) {
 	}
 else {
 	# Show text editing area
+	$sig = &html_to_text($sig) if (&signature_is_html($sig));
 	$wm = $config{'wrap_mode'};
 	$wm =~ s/^wrap=//g;
 	$wcols = $config{'wrap_compose'};