Open-Xchange continues to promote itself as an open source, SaaS-friendly alternative to Microsoft Exchange. The latest news hook:  Two more service providers will host Open-Xchange as a SaaS solution for end-customers. Word is Open-Xchange is looking to double their customer base and hit 40 million users in 2011, and they see better IT channel relations as the way to get there.

The service providers in question, California-based Lunarpages Internet Solutions and Cirrus Tech in Toronto, Canada, are replacing their existing hosted mail systems with Open-Xchange Hosting Edition, according to the press release.

Lunarpages says it tried hosted Exchange but found it unprofitable. But now that same press release indicates that Lunarpages plans to move 150,000 clients (with 750,000 e-mail accounts between them) to Open-Xchange webmail and offer additional services on top of it. Lunarpages will still offer Exchange, but the company will emphasize Open-Xchange.

As for Cirrus Tech, the company plans to replace 300,000 webmail accounts with Open-Xchange. And by using the OXtender for Plesk connector, Cirrus enables customers to manage and monitor their own mail accounts. What's more, Cirrus intends to integrate the platform with their VoIP offerings.

Open-Xchange seems to be gaining momentum with SaaS-focused channel partners. And the company's commitment to partners seems sincere. Open-Xchange hosted a partner summit in November 2010, which attracted scores of VARs, managed services providers (MSPs) and cloud services providers (CSPs). And CEO Rafael Laguna was on-message to partners throughout the event.

Meanwhile, numerous cloud services providers are rethinking their hosted email strategies -- especially as Microsoft Office 365 (the forthcoming successor to Business Productivity Online Suite) nears launch sometime this year. Intermedia, for instance, continues to offer hosted Exchange but has also introduced a hosted Unified Communications channel partner program.

Follow Talkin’ Cloud via RSS, Facebook and Twitter. Sign up for Talkin’ Cloud’s Weekly Newsletter, Webcasts and Resource Center. Read our editorial disclosures here.