diff --git a/src/main/java/co/cfly/email/impl/util/MailUtility.java b/src/main/java/co/cfly/email/impl/util/MailUtility.java
index 3fa2690..cd4b544 100644
--- a/src/main/java/co/cfly/email/impl/util/MailUtility.java
+++ b/src/main/java/co/cfly/email/impl/util/MailUtility.java
@@ -18,6 +18,7 @@
 import java.util.Enumeration;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.Properties;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -290,8 +291,9 @@ public static String decodeString(String value) {
     /**
      * Determines the content type of the part, or empty if it cannot determine
      */
+    @SuppressWarnings("SwitchStatementWithTooFewBranches")
     public static Charset determineCharset(Part part, Charset defaultValue) throws MessagingException {
-        return Arrays.stream(part.getHeader("Content-Type")).findFirst().map(value -> {
+        return Optional.ofNullable(part.getHeader("Content-Type")).flatMap(headers -> Arrays.stream(headers).findFirst()).map(value -> {
             Matcher matcher = CHARSET_EXTRACT.matcher(value);
             if (matcher.find()) {
                 String charsetName = matcher.group(1).trim().toUpperCase();
diff --git a/src/test/java/co/cfly/email/MailUtilityTest.java b/src/test/java/co/cfly/email/MailUtilityTest.java
index 777532a..9bb9fc8 100644
--- a/src/test/java/co/cfly/email/MailUtilityTest.java
+++ b/src/test/java/co/cfly/email/MailUtilityTest.java
@@ -32,6 +32,12 @@ public void determineCharset() throws MessagingException {
         Assert.assertEquals(StandardCharsets.UTF_8, MailUtility.determineCharset(part, StandardCharsets.UTF_8));
     }
 
+    @Test
+    public void determineCharsetNoContentType() throws MessagingException {
+        MimeBodyPart part = new MimeBodyPart();
+        Assert.assertEquals(StandardCharsets.UTF_8, MailUtility.determineCharset(part, StandardCharsets.UTF_8));
+    }
+
     @Test
     public void determineCharsetQuoted() throws MessagingException {
         MimeBodyPart part = new MimeBodyPart();