user account controls

@Bingobing

Can you tell us a little more about what you're trying to do?  I don't think I understand the problem fully based on what you'r provided so far.

"Webmail will delete unread email messages in your Inbox automatically after 60 days."

Is there a way to change this behavior, so messages persist until I delete them or retrieve them with an email client?

@RalJones

This behavior cannot be changed. If you wish to hold onto unread items longer than 60 days moving them to a user created folder would work.