Save the unaltered version in another variable, then munge it. End up with both versions at the end. The regex you use in the substitution depends on the real situation, but everything else should be basically the same.

#!/usr/bin/perl

while( <DATA> )
    {
    chomp;
    
    my $munged = $_;
    
    $munged =~ s/-(?:spam|ham)(?=@)//;
    
    printf "%-30s  -->  %-30s\n", $_, $munged;
    }

__END__
joe@example.com
joe-ham@example.com
joe-spam@example.com
joespam@example.com
wortham@example.com
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