for (@array)
        {
                s/0;nodata/1;$secondary/gi if /$email/
        }
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This would be (essentially) shorthand for:

        for my $_ (@array)   # 'my $_' is a little bit of a fudge
        {
                $_ =~ s/0;nodata/1;$secondary/gi if $_ =~ /$email/
        }
[download]

See perlvar for a little more explanation.