Why does XpdfPrint fail to print documents when running under Citrix?
The Citrix Universal Printer Driver spools EMF files, rather than "raw" (PCL, PS, etc.) files. XpdfPrint specifies raw spool files (for performance reasons); unfortunately this causes Citrix printing to fail (instead of just ignoring the raw mode flag).
As a workaround, you can tell XpdfPrint not to use raw mode, by setting the rawSpoolFile property to false (if using the printPDF4 API), or by using printNoRawSpoolFileFlag (if using the printPDF3 or earlier APIs).