Learn to Make iPhone Mail Keep Fewer Deleted Mail Items

It's easy to delete one or two emails in the iPhone Mail app with just a swipe. It is not so easy to delete a bunch of email at once: You still must select emails individually for deletion. 

When you delete an email, it isn't gone from your iPhone yet. It moves to the Mail Trash folder. You eventually have to remove the deleted email from the Trash folder, or your iPhone deleted email fills up space on your phone.

However, you can set iPhone Mail to remove all deleted mail after a day in the Trash folder, which takes care of taking out the trash. You start each day with no deleted emails in the iOS Mail Trash folder.

To tell iPhone Mail to remove deleted messages from the iPhone quickly:

1. Tap Settings on the iPhone's Home screen.
2. Go to Accounts & Passwords (or Mail, Contacts, Calendars). In early versions of iPhone Mail, tap Accounts.
3. Tap the desired email account in the Accounts list.
4. Scroll to the bottom of the screen and tap Mail in the Advanced section.
5. Tap Advanced at the bottom of the screen that opens.
6. Tap Remove in the Deleted Messages section.
7. Select After one day. (Other selections include After one week, After one month, and Never.)
8. Tap Save.

Now you never have to remember to empty the Trash folder in iOS Mail again. It is done automatically for you each day.

If you aren't comfortable with the iPhone emptying the Trash folder in the Mail app, you can do it quickly yourself. 

1. Open the Mail app.
2. On the Mailboxes screen, tap the Trash folder of the email account. If you use more than one email account, there is a section with a Trash folder for each account. 
3. Tap Edit at the top of the Trash folder screen.
4. Tap Delete All at the bottom of the screen and confirm the deletion.