SAP also provides services to at least one of the Guptas' businesses, VR Laser.
The leaked e-mails show that in March 2015 there were confidential meetings with various Sahara company executives at which they discussed, among others, a business rescue plan for CAD House.
It is not known why SAP entered into an agreement with the company to help secure the Transnet deal just months later, when it was still facing business rescue.
Professor Jannie Rossouw of Wits School of Economics said having insight into SAP's systems for outsiders would be like striking gold. "In economic terms this allows one to do 'front running' ... it comes down to insider trading."
He said access to SAP systems in state-owned entities would allow someone to potentially make huge profits off government tenders.
"You can see how a deal is being shaped and set yourself up as the ideal government partner, whereas you have no ideas on the projects."
The Guptas had not responded to questions at the time of going to print.