Written by Topher Kessler
OS X users who upgraded to 10.5.8 may run into a problem where Mail will not open, and instead gives an error stating that this version of Mail cannot be used with the current operating system.
Apple discussion poster "ebpries" writes:
"After installing the OS X 10.5.8 upgrade, I get a message "You cannot use this version of the application Mail with this version of Mac OS X" when I try to launch the Mail application. I looked, but there is no newer version of Mail available...my software is fully up to date."
This problem usually happens because Mail has been moved out of its default location when you have applied the system update. In 10.5.8, Apple released a new version of Mail, and changed system files such that the old version of Mail will no longer work. Having Mail in a location other than the Applications folder will result in two versions being on the computer: the old one and the new one.
To locate the new version that will work, you can try finding it in the Applications folder, or use Spotlight to search for Mail and then get information on the search results to see the location of the program. The new version of Mail is version 3.6, and the one that worked with OS X 10.5.7 was version 3.5.
This problem also seems to happen because of a bad link between the Dock and a properly updated version of Mail. Removing Mail from the Dock and then adding it back should clear this problem if you do not have multiple versions of Mail on your system.
Some final approaches to this problem may be to remove the Mail preferences file, which is called "com.apple.Mail.plist" and is located in the /username/Library/Preferences/ folder. Removing this file and relaunching Mail should prompt you for your account information again, but hopefully will clear launch problems, especially if you are able to open Mail in another local account. Additionally, you can try reapplying the combo updater, which should ensure files are in their proper locations. To do this, download the updater from here and then reboot into Safe Mode (to ensure minimal interference with the update process) and run the updater.
This problem is a clear example of why you should always move your Apple-supplied applications back to their default locations before upgrading your system. While it can frustrate some people's application organization, it is a good way to prevent these kinds of errors.
Topher has been an avid Mac user for the past 10-15 years, and has been a contributing author to MacFixIt for just over a year now. One of his diehard passions has been troubleshooting Mac problems and making the best use of Macs and Apple hardware both for family and friends, as well as in the workplace. He and the newly formed MacFixIt team are hoping to bring enhanced and more personable content to our readers, and keep the MacFixIt community going here at CNET. If you have questions or comments for Topher or the other MacFixIt editors, feel free to contact us at http://www.macfixit.com/contactResources