Access mail from internet

Hi everybody,We have 5 mail servers in our intranet. Some users will access to their mail from internet. We use Juniper Network SA4000 to allow this type of connection. When we use DWA through intranet, we have a response time of 4 seconds, but when we come through Juniper we have a response time of 5 minutes. Can you help me please…

Many thanks in advance.

Best regards,

Jean-François