I confess, I use my deleted items like a recycle bin. Delete and then leave for a few weeks (in case of error) and then delete for good. So how do you delete emails older than, say a month, automatically? Auto archive is the feature you need, it will also allow you archive emails to a folder or to a personal storage table .pst ( a local outlook file on your hard drive, which can be backed up and opened). Some people like to archive emails by year for example. A combination of rules and auto archive will do the trick.
Auto archive is configured in two places, globally in File | Options | Advanced | Auto Archive | auto archive settings.
The other place is at a folder specific level, in my example I delete anything older than a month from Deleted Items, junk mail can be deleted more often. Right click on folder (deleted items) to view properties| autoarchive | change settings |apply |voila… This does the job for permanently deleting from deleted items and would also cover off saving to a PST file but what about moving to another folder and then archiving?
First make a rule to find and move all the emails you require to the appropriate folder, and then set up archive rules on that folder. Rules, out of the box
Make a time based rule home|rules|create rules|advanced options|
fill in any desired criteria from list add in time constraint
|next scroll down to received in a specific time span and fill in the required dates. Sadly there is no option to specify relative times such as older than a week. But, if you are regularly moving emails based on time such as a quarter or year you specify that and redo the rule ready for the next batch.
Next|ok|next|move to specified folder (click on the underlined text as before) then finish. You will be asked if you wish to apply the rule now, click yes and all the emails meeting your criteria will move to the correct location and will continue to do so during the active time period.
Finally, archive, use auto archive to archive to your local .pst folder, which you can back up to disk using your regular back up routine. You do have a back up routine?
You can also set the pst file to be on a shared or cloud drive, bearing in mind any and all security risks and business policies in place which might constrain you from doing so.