Q. Under the platinum package, what is the size of mailbox, and what can be the maximum size of the email attachment?

Ans. You can setup mailboxes of unlimited quota as the actual filled data would be considered as your usage and it makes no difference what quota you assign while adding the mailboxes. If you fill up your single mailbox with 400Mb emails then you will exceed the quota assigned to your account. The maximum file size in an attachment is limited to 50MB.