Mac OS X 10.0 Mail: Mailbox Locked Alert

Symptom

When opening the application Mail, you may get an alert box with a message like this:

"The mailbox ~/Library/Mail/Mailboxes/INBOX.mbox is currently locked by username on host myhost.com. If you open a mailbox that is already in use, you may damage its contents."

Notes

1. The exact message varies depending on the name of the Mail user and the host name.
2. The tilde (~) represents a user's Home directory.

A dialog box offers three choices:

• Open Read Only
• Quit
• Open Anyway

Solution

Update to Mac OS X 10.1 or later.


There are three reasons why this alert could occur.

Application did not quit properly

If the application Mail stopped responding or quit unexpectedly during its last use, it may not have been able to properly close the files. It is safe to click Open Anyway in this case.

Changing network connection

This alert could occur if you change networks while Mail is open. Some examples include:

• Disconnecting from an Ethernet network and connecting to an AirPort network.
• Changing from Ethernet to dial-up PPP.
• Changing the configuration of an Ethernet connection (static IP to DHCP, for example).

In these cases it is also safe to click Open Anyway.

Multiple accounts in Personal Mailboxes

This issue can happen when:

• Two or more mail accounts are set to deposit messages in the Personal Mailboxes Inbox.
• Messages from two or more accounts are subsequently written to the Inbox at the same time.

To work around this, you either create a separate Inbox for each account or check your accounts individually.

Note: The first workaround is only available for POP accounts. IMAP accounts automatically have a separate Inbox. A Mac.com account may be set up as either POP or IMAP.

Follow these steps to create separate Inboxes:

1. Choose Preferences from the Mail application menu.
2. Click to select the name of an account in the Description column of the Mail Preferences window.
3. Click Edit.
4. Click the Account Options tab.
5. Click the radio button to enable the "Show this account separately in mailboxes drawer" option.
6. Click OK.

To check your accounts individually, choose Get New Mail In Account from the Mailbox menu. You also need to set your accounts to check mail manually. To do that:

1. Choose Preferences from the Mail application menu.
2. Choose Manually from the Check accounts for new mail pop-up menu.