Zimbra and Yahoo Public License

[Allard Hoeve <allard@byte.nl>]

Hello All,

I'd like to try to package Zimbra for Debian.

Zimbra is at http://www.zimbra.com/. It is distributed according to the 
Yahoo Public License, which you can read at 
http://www.zimbra.com/license/yahoo_public_license_1.0.html

Is the Yahoo Public License DFSG-compatible? I haven't found anything that 
made me believe otherwise but the license does state for example:

"Subject to the terms and conditions of this Agreement, __Yahoo!__ hereby 
grants to You, under any and all of its copyright interest in and to the 
Software, a royalty-free, non-exclusive, non-transferable license to copy, 
modify, compile, execute, and distribute the Software and Modifications."

(emphasis mine)

What does the debian-legal community think?

Thanks!

Regards,

Allard Hoeve