In the first round Microsoft announced a US$500 million advertising campaign directly targeted at IBM Global Services. The People Ready campaign carried the message "Innovation is home-grown, it's not outsourced," according to Jeff Raikes, President of Microsoft's Business Division.

IBM quickly retorted that the campaign was little more than Window dressing for a pitch to keep "a one-size-fits-all, proprietary Windows world".

But Big Blue, which has been pursuing the Penguin for some time now, has now stepped up the pressure on Microsoft with a bounty to be paid to US resellers who encourage businesses to replace their Exchange infrastructure with IBM's Notes/Domino solution on Linux.

The US$20 per seat rebate will be available to more than 100 participating partners as part of IBM's "Migrate to Penguin," program - an extension of its Move2Lotus program.

Big Blue says the move counters a program launched by Microsoft in January. However, Microsoft's January offering didn't involve any cash bounties, just some migration tools.

The US$20 rebate per seat, is capped at 1,000 seats or US$20,000, but bundles some other goodies such as free education and certification to bring partners up to speed on Lotus Notes and Domino 7 development skills, and a hosted proof-of-concept component that allows customers to try before they buy on a Domino server environment.

Although Microsoft is the market leader in email and collaboration with a 51 per cent share according to IDC, IBM has successfully snatched nearly 3,000 Exchange and other platforms users to Notes/Domino in the two years since those programs launched, according to reports.