Q: OS X wants to make changes. when sending mail

Please back up all data before proceeding.

This procedure will unlock all your user files (not system files) and reset their ownership, permissions, and access controls to the default. If you've intentionally set special values for those attributes on any of your files, they will be reverted. In that case, either stop here, or be prepared to recreate the settings if necessary. Do so only after verifying that those settings didn't cause the problem. If none of this is meaningful to you, you don't need to worry about it, but you do need to follow the instructions below.

Step 1

If you have more than one user, and the one in question is not an administrator, then go to Step 2.

Triple-click anywhere in the following line on this page to select it:

sudo find ~ $TMPDIR.. -exec chflags -h nosappnd,noschg,nosunlnk,nouappnd,nouchg {} + -exec chown -h $UID {} + -exec chmod +rw {} + -exec chmod -h -N {} + -type d -exec chmod -h +x {} + 2>&-

Copy the selected text to the Clipboard by pressing the key combination command-C.

Launch the built-in Terminal application in any one of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Paste into the Terminal window by pressing command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.

You'll be prompted for your login password, which won't be displayed when you type it. Type carefully and then press return. You may get a one-time warning to be careful. If you don’t have a login password, you’ll need to set one before you can run the command. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.

The command may take several minutes to run, depending on how many files you have. Wait for a new line ending in a dollar sign ($) to appear, then quit Terminal.

Step 2 (optional)

Take this step only if you have trouble with Step 1, if you prefer not to take it, or if it doesn't solve the problem.

Start up in Recovery mode. You may be prompted to select a language, then the OS X Utilities screen will appear.

If you use FileVault 2, select Disk Utility, then select the icon of the FileVault startup volume ("Macintosh HD," unless you gave it a different name.) It will be nested below another drive icon. Click the Unlock button in the toolbar and enter your login password when prompted. Then quit Disk Utility to be returned to the main screen.

Select

          Utilities ▹ Terminal

from the menu bar. A Terminal window will open. In that window, type this:

resetp

Press the tab key. The partial command you typed will automatically be completed to this:

resetpassword

Press return. A Reset Password window will open. You’re not going to reset a password.

Select your startup volume ("Macintosh HD," unless you gave it a different name) if not already selected.

Select your username from the menu labeled Select the user account if not already selected.

Under Reset Home Directory Permissions and ACLs, click the Reset button.

Select

           ▹ Restart

from the menu bar.

I would need to know something about which permissions you've changed and why. If you don't want to disclose that information, that's understandable, but then I can't make any other suggestions.

It sounds like you're trying to use the system in a way it wasn't designed for. The closest I can come to making a useful suggestion is that you should never change the ownership of any of your files. If you insist on allowing special access to specific users, do it by adding entries to the Sharing & Permissions section of the Info dialog in the Finder. Depending on what you're trying to do, you may need to learn about access control lists, which you can do by reading the chmod(1) UNIX manual page. ACL manipulation is only suitable for advanced users.

There are two other possible reasons for this behavior.

1. You installed a third-party Mail plugin such as "GPGMail." Either remove it according to the developer's instructions or refer to the developer for support.

2. You imported a mail-signing certificate into the System keychain. It belongs in the login keychain (or the iCloud keychain, if applicable.)

Launch the Keychain Access application and locate the certificate in the System keychain. Drag it into the login or iCloud keychain. You may be prompted twice for the administrator password.