More than 50% of enterprise email and collaboration systems, measured by users, will be hosted in the cloud by 2020, according to a report from IT analyst group Gartner.

Cloud email and collaboration services, which Gartner has given the acronym CECS, currently accounts for between 3% and 4% of the total market. However, this will grow to 10% by 2014, 20% by 2016 and 55% by 2020, the company predicts.

Gartner had previously predicted that market penetration would be greater than 10% by 2014 but downgraded its estimate as adoption has been slower than expected. Analyst Tom Austin said this due inertia, IT managers’ focus on more business-related initiatives, and what Austin called "practical realities".

"The practical realities of the vendors’ CECS offerings, when examined up close, are sometimes less compelling than the glossy stories they tell," he said.

The report noted that many businesses that have moved most of their email systems into the cloud have also kept a dedicated, on-premise system in order to manage emails between executives.

Gartner also announced that it now considers Google’s Gmail to be a viable cloud alternative to Microsoft for enterprise email systems.

However, it said that Gmail’s lack of back-end feature development would hold it back in capturing specialist customers like financial institutions. According to some large enterprises, Google’s lack of transparency in areas such as continuity, security and compliance can thwart deeper relationships, the company found.

Gartner analyst Matthew Cain said that Gmail should now be considered a mainstream cloud email product. "The rivalry between Microsoft and Google will make it difficult for other suppliers to compete directly in the cloud email and collaboration space," Cain said.