When migrating from NW51, you need to load sms with code page of NW51 server.
On NW server use the command "language" to get the code page of NetWare server
On Linux, open the file /etc/opt/novell/sms/tsafs.conf, add the following line useCodeSet=123
Where 123 is the code page on NetWare server.
After that restart SMDR daemon using the command "rcnovell-smdrd restart"
These steps are documented in OES2 Migration Guide