Q: How do I manage old emails

Conditions:  "Date Received"           "Is Greater Than 180 Days"

Actions: Delete Messages

Note that rules normally only get applied to New Unread incoming messages. So, I'm not sure if they will get applied using the time factor, but I haven't tried that.

You would do that from a computer. Open Mail's preferences, and select the Rules tab. Conditions would be when you create a rule, the criteria at the top portion you would put. However as I said, I doubt it will work because of the way rules are applied automatically. You would have to select all messages and apply the rule manually. I could never get that to work automatically.

Possibly a better option would be to create a Smart Mailbox with that criteria. A smart mailbox is more of a search function and don't actually contain messages. They just point to the messages meeting the criteria no matter which mailbox they actually reside in. Actions can't be set to perform manually, but you can select the mailbox at your convenience and delete the messages within. They will be removed from whatever mailbox they are in.

I understand about wanting it to act on messages automatically by setting the date range, but I never found a way to get it to work. As I said, rules are only applied to New Unread messages. If they are read by another device first, then rules don't get applied.

They can be applied manually, but then you would have to select all messages you want to apply them too.

There are extensions you might look into for the Mail application that might enable you to apply rules per your desired settings. You will have to investigate those as I am not familiar with using any of those.

For the simple solution in Mail, the Smart Mailbox is the better option even though you will have to manually select and delete the messages. At least you won't have to search for messages 6 months or older. They will be shown there.

The only other option is to use a more advanced email application such as Outlook. It may have the features you require.

Gmail has very basic filters which you can apply there. However, there are no criteria for date range. Most email providers only provide very limited filters. As I said, maybe a more advanced Mail application will have what you need.

You can go to Gmail's webmail site and check that out for yourself under settings, then Filters.

Another thought would be to use Automator to create a script to do what you want. I'm not very good with Automator, so you might create another discussion on the topic of using Automator to delete mail messages older than your date range.

An extension such as Mail Act On will give you some options to how you can enable rules and run them manually. How it works and how much control you have will have to be investigated by you. I've never used it. There may be other extensions for Mail that will work with rules, but I'm not aware of them.

I'm not really a big fan of using 3rd party apps, extensions, or advanced scripts to change the function of an application such as Mail. It can create more problems than it will solve.

If you manage a ton of mail and really need this, then you should look into these other options. However if it's only a minor distraction, the Smart Mailbox is still the best option because it's a basic function of Mail and you have total control of what happens.