The SALES module from Custom Gateway includes tools to aid in the management of customer service enquires managed between retailers and fulfillers.

On each order within the Order Manager tab there is a section called "Customer Service". This area is made to allow retailers to enter in a message and add any supporting attachments for fulfillers who are using this feature. See screenshot below.

When a comment is submitted here it will be tracked in the order history and timestamped. It appears for the fulfiller under the "Customer Service" tab in the Sales menu. 

These will appear as below, fulfillers can see the comment provided and have the ability to deal with a close off the comment and also duplicate the order if a resend is needed.