Many OS keep there sendmail program in different places,
in these situations it is common to find that the OS provide their own packages for the Perl Modules:
like here for Mandrake (as one for instance).
In these situations it is better to forsake perl -MCPAN -e 'shell' for RPMs in your case.

Alternatively you could use symlinks to cobble a solution.

--

Brother Frankus.

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