All  ... I saw several old articles about this issue but I haven't seen any lately and I never saw a good solution!

Starting last week about 15% of our credit card trancations are giving hte user this message:

The reporting of this transaction to the Merchant has timed out. An e-mail has been sent to the merchant informing them of the error. The following is the result of the attempt to charge your credit card.

This transaction has been approved.

It is advisable for you to contact the merchant to verify that you will receive the product or service.

I then get this e-mail from Authorize.net ... 

Authorize.Net Merchant,

Your script timed out while we were trying to post transaction results to it.

   Transaction ID: nnnnnnnnnnnn

Transaction Result: This transaction has been approved.

After much research ... 

1. The post for the relay response never reaches our servers

2. The time out on the relay response is supposed to be 10 seconds but it happens in some cases immediately

In old threads (from 2010) I saw people changing their DNS TTL to 1 week ... I will try that.

Any other ideas?  Do I need to get off of SIM?  Authorize.net support couldn't help.