java.lang.NoClassDefFoundError: Could not initialize class com.aspose.email.ay

My problem occurs with several emails but there doesn't seem to be a problem with the email.

I'm batch exporting hundreds to thousands of messages. I can't reproduce the exception

if I run an export with just the message that causes the problem during batch processing.

I'm seeing sporadic exceptions like this:

Caused by: java.lang.NoClassDefFoundError: Could not initialize class com.aspose.email.ay

at com.aspose.email.am.<init>(Unknown Source)

at com.aspose.email.kv.<init>(Unknown Source)

at com.aspose.email.bD.<init>(Unknown Source)

at com.aspose.email.hK$o.a(Unknown Source)

at com.aspose.email.hK.a(Unknown Source)

at com.aspose.email.av.a(Unknown Source)

at com.aspose.email.aq.a(Unknown Source)

at com.aspose.email.MapiMessage.d(Unknown Source)

at com.aspose.email.MapiMessage.b(Unknown Source)

at com.aspose.email.MapiMessage.fromMailMessage(Unknown Source)

I'm using linux. My jar is aspose-email-3.6.0.0-jdk16.jar.

java version "1.7.0_17"

Java(TM) SE Runtime Environment (build 1.7.0_17-b02)

Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode)

Do you have suggestions on possible workarounds?