You’ve run into a problem: the Mail icon bounces endlessly in the Dock (and the pointer may or may not change to a spinning beach ball), or it unexpectedly quits and presents you with a window indicating such. How can you solve this frustrating event?
Perform the following steps—in order and one at a time—until you solve your problem. The solutions increase in severity (in terms of potential data loss), so you want to stop once Mail will open. Create a new folder on the Desktop before you begin, as steps 2-4 require you to temporarily remove files from existing folders, and storing them on the Desktop allows you to quickly restore your data.
Accessing Your Address Book
Mail needs to be able to access the contents of your Address Book, even if it is empty. If Mail will not open, there is always the chance your file permissions are simply incorrect. If you no longer have the ability to open the Address Book or modify its entries, select Address Book in the Finder. From the File menu, select Get Info. The window that appears will have a section called “Permissions.” By default, you should see three names listed in the “Name” column: system, wheel, and everyone. Make sure system has “Read & Write” privileges. Alternatively, you can click the plus button and add your user to the list, making sure it has read and write privileges. You may need to click the padlock at the lower right corner and enter your administrator password to make these changes.
Managing Mail Plug-ins
If Mail still will not open, you may have installed a plug-in that is now corrupt or incompatible. Navigate to the InputManagers folder inside the top-level Library folder. If there are no items in this folder, proceed to the next troubleshooting step. Otherwise, drag all of the items from this folder to the new folder you created on the Desktop, and reopen Mail. If Mail opens properly, one of the InputManagers is the culprit. You should place one InputManager at a time back in its folder, restarting Mail each time, until Mail no longer opens. The last InputManager replaced is the one causing the problem. You can try updating to a newer version, reinstalling the existing version, or simply removing that file to solve the problem.
Changing Mail Preferences
Mail’s preferences may also become corrupt. To test this, navigate to your user Library folder and open its Preferences folder. Move com.apple.mail.plist to the Desktop. Try reopening Mail. If Mail does not open successfully, the preferences were likely not at fault. However, Mail may have created new preference files when you tried to open it. You should move your old preference file from the Desktop back to the Library Preferences folder (choosing to replace the existing preferences, if necessary).
If removing your Mail preferences did allow Mail to open, this presents a slightly more annoying problem: your email data remains intact, but your settings disappear. While you lose small settings, such as font preferences and window sizes, Mail also “forgets” that you have email accounts installed. If Mail cannot find any existing accounts, it first tries to configure your MobileMe account, assuming you have registered it in the MobileMe System Preference. Otherwise, Mail opens to its configuration window and asks you to enter your email account details. After entering this information, your existing email messages and folder may have returned, but if not, continue reading to learn how reinstall your folders.
Checking Mail Folders
It is common for Apple’s Mail to store hundreds of thousands of files in its data folders, especially if you keep all of your mail from years ago. Fortunately, it is uncommon for these files to become so corrupt that Mail no longer opens. There is an easy way to test this, however. While Mail is closed, navigate to your user Library folder and drag the Mail folder to the Desktop. Reopen Mail. If Mail successfully opens, either your mail messages or your mail folder settings are corrupt. Unfortunately, the “quick fix” for this problem is to no longer use your mail folders (i.e. delete your mail). Most people do not want to lose their mail, and if your mail server does not keep copies of your messages on it, deleting these folder means you rebuild your mail accounts from scratch. Luckily, Apple’s Mail does have an easy way to rebuild messages and folders, so if you want to try this, read the article on Importing and Rebuilding Mail.
Did this guide work for you? How else have you been able to get your Mail.app to open when it otherwise wouldn’t? Let other readers know in the comments.