Research in Motion (RIM) is offering a free copy of its BlackBerry server software in the hope of persuading more small businesses to buy into its push email service, long perceived as a big-business offering.

The SME version is - functionally, at least - identical to the BlackBerry Enterprise Server standard offering, version 4.1. Dubbed BlackBerry Enterprise Server Express, the software can be downloaded and used to provide email services - assuming the user has a suitable data deal with a mobile phone carrier - to a single user. Companies can buy licences to provide email for up to 14 more users.

Anyone wanting to support more than 15 users needs to upgrade to BlackBerry Enterprise Server 4.1, for which they'll need to purchase an electronic key to convert the download from Express to the full version.

RIM said the Express software will run alongside Microsoft Exhange, Lotus Domino, and Novell Groupwise. To download the software, users need to own at least one Blackberry device - you need its PIN to authorise the download.

RIM already offers a SME-oriented version of its server software, BlackBerry Enterprise Server Small Business Edition, but as it wants $1,099 for it from US customers, the Express release does mark something of a saving. Extra user licences cost $99, in addition to the cost of the devices they will use and the BlackBerry service subscription.

As RIM makes most of its money from hardware sales, it can undoubtedly afford to subsidise its server software this way, particularly if it encourages smaller companies to take advantage of its offer. ®

You can download the software here.