At the risk of heresy, why would you need perl for this? Command lines like this:

find / -mtime +7 -o -size +5000000c | mail -s 'Old and big files' mikf
+ire
[download]

have been around and used for a long time.

If you wanted to get fancy, you could even try:

find / -mtime +7 -o -size +5000000c -ls | mail -s 'ls of Old and big f
+iles' mikfire
[download]

which will basically dump a stat(3) on each file.

Seeking the proper tool for the job at hand,
mikfire