hi all there.

i installed Zimbra Client for my clients to access emails. But when they send email of above 5MB it is giving me error and msg bounce back to inbox with the following error

Subject: Delivery Failure Notification: message size exceeds server limit

Your message "register only" sent on أبريل 19, 2011 at 8:53 ص to "email<email@email.com>" can't be delivered. None of the recipients will receive the message. It has been returned to Drafts folder for your review.

Is there any problem in my settings or from where i can increase the limit of Size

Please Guide