Ralf Hildebrandt is an active and well-known figure in the Postfix community, working as a systems engineer for T-Systems, a German telecommunications company.
He speaks about Postfix at industry conferences and hacker conventions and contributes regularly to a number of open source mailing lists. Ralf Hildebrandt is co-author of The Book of Postfix.
Huang Zhen is a software engineer at IBM China Development Labs.
He has been working on the Linux-HA project since 2004 and contributed several components to the project.
PAM-related functions in the Linux-HA project were developed by him.