PostPath has added support for push email devices, including the BlackBerry, in the latest version of its namesake server software.

PostPath 3.0 can push messages out to BlackBerries and rival mobile devices that run either Windows or the Palm OS operating system.

The company makes a Linux-based email server, and is one of many third-party vendors that claim to provide true or near-true compatibility with Microsoft's market-leading Exchange.

PostPath Server 3.0 supports Research In Motion's BlackBerry Enterprise Server (BES) software as well as ActiveSync, Microsoft's rival handheld synchronisation software. "Other than Exchange itself, we are the first to support both," said PostPath CEO Duncan Greatwood.

Microsoft has built ActiveSync into Exchange Server 2007, and ActiveSync also has been adopted by handheld vendors such as Motorola, Nokia and Palm. In addition, Apple is rumoured to be looking at adding ActiveSync support to the iPhone.

Michael Osterman, an analyst at Osterman Research said that supporting both BES and ActiveSync could help PostPath save its customers money. For instance, if PostPath Server didn't support both, users might have to buy an extra BES-equipped system to support their BlackBerry-toting employees.

An enterprise version of BES costs $2,999 with a single user licence or $3,999 with 20 user licences, according to pricing information on RIM's website. Additional client licenses start at $99, or $429 for a package of five licences.

Greatwood claimed that PostPath Server 3.0 is also more efficient and can support more simultaneous users than Exchange itself. "It's quite realistic now to put thousands of mobile users on a PostPath server," he said, adding that the software can support 500 times more synchronisation attempts at one time than Exchange can.

Osterman said he thinks that the first claim - that PostPath can support thousands of mobile users - is "impressive." But he said the second one - the boasts that PostPath can handle 500 times as many simultaneous synchronisation attempts as Exchange - sounds "awfully high."

According to Greatwood, PostPath has "hundreds of paying customers," and its software supports more than 100,000 end-users overall.

He also said that PostPath's webmail client has been improved as part of the software upgrade. The client software was created from the same open-source code as a product offered by Zimbra, which is being acquired by Yahoo under a deal announced last month.