Is there a way to limit Mail to only keep the last 50 mails?
Solution 1:
Mail can do something sorta like what you want.
- Mail > Preferences
- Accounts tab
- Mailbox Behaviors tab
- Trash section
On the line that says "Permanently erase deleted messages when", you can select one month old or one week or even one day. That will help get rid of old email and save you some space.