Scripted around this issue with the following as /home/sogo/bin/sogo-ealarms-notify-cron and then set the cronjob to run it instead.
#!/bin/sh
export LD_LIBRARY_PATH=/home/sogo/GNUstep/Library/Libraries:/usr/GNUstep/Local/Library/Libraries:/usr/GNUstep/System/Library/Libraries
/usr/GNUstep/System/Tools/Admin/sogo-ealarms-notify
