It is possible to get the mail service to automatically expire and delete messages from selected folders after a certain period of time has elapsed from when it was delivered to you.
This can be useful for limiting the size of mail folders such as where suspected spam messages are stored. For example, you can set the option on a folder to delete any messages that are older than 30 days. Once a message in that folder has been there for longer than that period then it will be automatically deleted. Use this option with care though, and select a period of time that will be long enough to ensure that you will have seen the message and been able to have dealt with it if necessary.
To set the expiry time on messages in folders, open the folder management screen by clicking on Folders and select the folders you want to have expired and then select Select Message Expiry Times for Folder(s) from the drop-down menu.
You will be prompted to enter the number of days that messages should remain in your selected folders. Once selected this setting will appear next to each folder name with an expiry time and also below the quota line in a mailbox listing.
To remove an expiry time from a folder set the expire time to be 0 days.
Message expiry times refer to all messages within the selected folder. It is not possible to have different expiry times on each message within a single folder.