If you use the same POP email account on more than one device, email messages might appear only on the first device that gets them. This happens when an email app is set up to automatically remove messages from the server after it receives them.
You can set up your iPhone, iPad, iPod touch, or Mac to keep messages on the server, delete them after a certain number of days, or keep them until you move them from your inbox. Follow these steps.
If your email account uses IMAP instead of POP for incoming mail, your email provider keeps new messages until you delete them, instead of until you retrieve them. So your mailbox stays the same on each device.

iOS Mail
Mail deletes messages from the server one week after deleting them from your device. This gives you time for other email apps— like OS X Mail—to download a copy of the messages. To change these settings:
- Go to Settings > Mail, Contacts, Calendars.
- Tap the email account that you want to change.
- Tap Advanced, then tap Remove.
- Choose a time frame.
- Tap Done to save your settings.


OS X Mail
Complete these steps on every Mac that uses the same email account:
- Open the Mail app, then choose Preferences from the Mail menu.
- Click Accounts, then select your POP account from the list of accounts.
- Click the Advanced tab.
- To keep new messages on the email server so that other devices can also retrieve them, follow either of these steps:
- Deselect the “Remove copy from server after retrieving a message” checkbox.
- Or select the checkbox, then choose an option from the pop-up menu. If you choose “Immediately,” your email provider deletes its copy of a message after Mail retrieves it. If you choose “When moved from Inbox,” your email provider deletes its copy of a message as soon as you move the message out of your inbox.

- Close Mail preferences to save your settings.

About POP locking
POP accounts support one connection at a time. If you use multiple devices to access your account at the same time, the devices might get locked out of the account. As a result, you might see a message that there are too many connections at the same time, or you might be asked for the account password. Wait about 20 minutes before trying again, or contact your email service provider for help.