> [...] HP unix server [...]

   Not a very detailed description of anything.

      uname -a

> [...] but not not send a mail attachment [...]

   What, exactly, is seen in the bad e-mail message?

> uuencode /home/perl/test.txt | mailx -s "test.txt - test2" -r
>  pra.wan@lokp.com ravi.pa@sipm.com pai.sum@tick.com

   So, you're using the same command/program(s) to send e-mail to three
recipients, and one of them does not see an attachment?  I know nothing,
but I would look at the e-mail _client_ programs being used by the
different recipients, not at the program(s) which are apparently sending
the attachment to at least some of the recipients. 

   Using uuencode this way is an old (obsolete), pre-MIME method of
sending attachments, and some newer e-mail clients may not handle it
properly.  A Forum search for keywords like, say:
      e-mail attachment
should find examples of newer methods (mpack, ...) which may work
better with more (newer) e-mail client programs.