diff --git a/FAQ.md b/FAQ.md
index a5e425ea7e..69270188d2 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -2780,6 +2780,7 @@ The following extra functions are available:
 * *hasMx()* (returns a boolean indicating if the from/reply-to address has an associated MX record; since version 1.2179)
 * *attachments()* (returns an integer indicating number of attachments; since version 1.2179)
 * *Jsoup()* (returns an array of selected strings; since version 1.2179)
+* *Size(array)* (returns the number of items in an array; since version 1.2179)
 
 Example conditions:
 
diff --git a/app/src/main/java/eu/faircode/email/ExpressionHelper.java b/app/src/main/java/eu/faircode/email/ExpressionHelper.java
index 60614c75ed..754cccec41 100644
--- a/app/src/main/java/eu/faircode/email/ExpressionHelper.java
+++ b/app/src/main/java/eu/faircode/email/ExpressionHelper.java
@@ -94,6 +94,7 @@ public class ExpressionHelper {
         MxFunction fMx = new MxFunction(context, message);
         AttachmentsFunction fAttachments = new AttachmentsFunction(context, message);
         JsoupFunction fJsoup = new JsoupFunction(context, message);
+        SizeFunction fSize = new SizeFunction();
 
         ContainsOperator oContains = new ContainsOperator(false);
         ContainsOperator oMatches = new ContainsOperator(true);
@@ -107,6 +108,7 @@ public class ExpressionHelper {
         configuration.getFunctionDictionary().addFunction("hasMx", fMx);
         configuration.getFunctionDictionary().addFunction("attachments", fAttachments);
         configuration.getFunctionDictionary().addFunction("Jsoup", fJsoup);
+        configuration.getFunctionDictionary().addFunction("Size", fSize);
 
         configuration.getOperatorDictionary().addOperator("Contains", oContains);
         configuration.getOperatorDictionary().addOperator("Matches", oMatches);
@@ -343,6 +345,25 @@ public class ExpressionHelper {
         }
     }
 
+    @FunctionParameter(name = "value")
+    public static class SizeFunction extends AbstractFunction {
+        SizeFunction() {
+        }
+
+        @Override
+        public EvaluationValue evaluate(
+                Expression expression, Token functionToken, EvaluationValue... parameterValues) {
+            int result = 0;
+
+            if (parameterValues.length == 1 &&
+                    parameterValues[0].getDataType() == EvaluationValue.DataType.ARRAY)
+                result = parameterValues[0].getArrayValue().size();
+
+            Log.i("EXPR size()=" + result);
+            return expression.convertValue(result);
+        }
+    }
+
     @InfixOperator(precedence = OPERATOR_PRECEDENCE_COMPARISON)
     public static class ContainsOperator extends AbstractOperator {
         private final boolean regex;
diff --git a/index.html b/index.html
index bdceee734c..7586d3ea29 100644
--- a/index.html
+++ b/index.html
@@ -1521,6 +1521,7 @@ X-Google-Original-From: Somebody &lt;somebody+extra@example.org&gt;</code></pre>
 <li><em>hasMx()</em> (returns a boolean indicating if the from/reply-to address has an associated MX record; since version 1.2179)</li>
 <li><em>attachments()</em> (returns an integer indicating number of attachments; since version 1.2179)</li>
 <li><em>Jsoup()</em> (returns an array of selected strings; since version 1.2179)</li>
+<li><em>Size(array)</em> (returns the number of items in an array; since version 1.2179)</li>
 </ul>
 <p>Example conditions:</p>
 <p><code>header("X-Mailer") contains "Open-Xchange" &amp;&amp; from matches ".*service@.*"</code></p>