diff --git a/src/com/android/exchange/EasSyncService.java b/src/com/android/exchange/EasSyncService.java
index 77f326016..0f2a34594 100644
--- a/src/com/android/exchange/EasSyncService.java
+++ b/src/com/android/exchange/EasSyncService.java
@@ -208,6 +208,12 @@ public class EasSyncService extends AbstractSyncService {
             userLog("Validation (OPTIONS) response: " + code);
             if (code == HttpStatus.SC_OK) {
                 // No exception means successful validation
+                Header commands = resp.getFirstHeader("MS-ASProtocolCommands");
+                Header versions = resp.getFirstHeader("ms-asprotocolversions");
+                if (commands == null || versions == null) {
+                    userLog("OPTIONS response without commands or versions; reporting I/O error");
+                    throw new MessagingException(MessagingException.IOERROR);
+                }
                 userLog("Validation successful");
                 return;
             }