Over the past month Nokia, Intellisync, Sproqit, Siemens, Smartner, Good Technology and Visto have all come up with mobile e-mail systems to compete with those from RIM.
With push e-mail users receive e-mail messages automatically on their mobile devices, via GPRS mobile networks, once the messages have been sent to a user's mail server.
The e-mail server is connected to a gateway that passes e-mail messages from the user's inbox, across a mobile operator's network and onto a device equipped with suitable client software, such as the Blackberry client.
Users can respond directly to the e-mails they receive and their sent mail is replicated across the mobile network, through the gateway and onto the e-mail server database.
Such systems are easy to deploy and often require little preparation and user training.
Analyst Gartner predicted that by 2008, 80% of staff will use push e-mail. Until recently, the Blackberry was the only widely available device. Globally, there are well over 20,000 RIM Enterprise Server systems installed.
According to Gartner, Intellisync is one of the closest to RIM in terms of market reach, financial backing and product features. And Intellisync's product is also device-independent, as opposed to RIM's main focus on supplying its Blackberry devices supported by its software installed on corporate servers.
Intellisync has launched version 6 of its operating software and is trying to win market share from RIM by signing deals with mobile operators across Europe.
The company's software is also loaded onto mobile phones from most of the big manufacturers.
RIM is now making sure this happens with its software via its Blackberry Connect programme, so it will not have to rely on the established Blackberry devices for revenues.
Nokia is ensuring its phone users are not limited to these two, however. It recently announced it was loading push e-mail software from Good Technology and Smartner on some of its phones.
Gartner said that if companies simply want wireless e-mail, then RIM is still a good bet. But it added that for superior data synchronisation covering all types of files, better device management and security, it is worth considering other options.
Rip Gerber, vice-president of Intellisync, said the company's software for servers is similar in price to RIM's when it comes to basic push e-mail, but admits it is more expensive when extra functionality is needed.
Such functionality is illustrated by a deal with PeopleSoft. Here PeopleSoft users can access business applications using Intellisync software.
While RIM recently launched the latest version of its operating software, which improved support for Lotus Notes and Novell Groupwise, the challenge to Blackberry's supremacy is clear as far as Visto is concerned.
Launching the latest version of Visto's push e-mail software, its chief executive Brian Bogosian, said, "We have strong mobile operator partnerships, the financial strength and the intellectual property that will allow us to surpass RIM's total subscriber base next year."