Error Message: Mail could not be saved

Are you sure Preferences > Accounts > Mailbox Behaviors > Store messages on the server is unchecked for Drafts and Sent?

What causes this problem in AOL accounts is precisely that AOL doesn’t let mail clients create mailboxes at the root level of the account directory on the server. In the case of AOL you must turn OFF Store messages on the server for all the mailboxes in Preferences > Accounts > Mailbox Behaviors, so that those mailboxes are stored locally instead, to avoid precisely this kind of problems.

Can you create custom “On My Mac” mailboxes in Mail by means of Mailbox > New Mailbox or does Mail complain with some error message when you try to do that as well?

OK. We’ll have to investigate what’s going on here.

Sent but not Saved messages do show when I open the remote server icons.

I don’t understand this. What do you mean?

Report the names of the files and folders present at the first level of the ~/Library/Mail/ folder in the Finder.

In order to post the exact file names and avoid typing mistakes, proceed as follows. In the Finder, go to ~/Library/Mail/. With that folder open, if you’re looking at it in View > as List mode, first collapse any expanded folders so that the Finder only shows the files and folders at the first level of ~/Library/Mail/. Now, do Edit > Select All (⌘A), then Edit > Copy (⌘C), and paste it in your reply to this post.

Before actually posting that information, edit it so that the file/folder names do not reveal any details you should keep private, e.g. replace any real username with “username” to hide your real email address. Other than that, report the file/folder names as accurately as possible.

Now, go to ~/Library/Mail/Mailboxes/. With that folder open, repeat the procedure to let me see the names of the files and folders it contains. Again, you may disguise any mailbox names you wish to keep private. Be careful to not alter any suffixes, though.

Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder. That is, ~/Library is the Library folder within the user’s home folder, i.e. /Users/username/Library.

So you have not one but three AOL mail accounts, right? Does the same problem happen with all of them? Are the Mailbox Behaviors settings the same for all of them? Doesn’t it make a difference choosing another account from the Account popup menu when composing a new message?

when I open any of those server folders there are messages in the Sent Items
sub-folder, but not in the Saved folder.

So what would you expect to see in Saved?

AOL automatically saves the messages you send through its outgoing server in a server-stored Sent Items mailbox that Mail has no control over no matter what your settings — and from which messages may be purged after some time, again without Mail’s intervention and no matter what your settings.

Saved, on the other hand, is the only AOL’s server-stored mailbox that‘s under the user’s control. Don’t expect to see there anything you haven’t moved there yourself. I believe you can tell Mail to create your own custom subfolders there if you wish by means of Mailbox > New Mailbox (select Saved first to tell Mail that you want to create the mailbox as a subfolder of Saved).

BTW, please update the Operating System field on your My Settings’s profile (and click Save), so that it accurately reflects the version of Mac OS X you’re running now.

I don’t know what’s going on here. I’d set up Mail again from scratch, check that things work fine, then import your mail back afterwards as follows:

1. Quit Mail if it’s running.

2. In the Finder, go to ~/Library/. Move (not copy) the entire Mail folder out of there, to the Desktop.

3. In the Finder, go to ~/Library/Preferences/. Locate com.apple.mail.plist and move it to the Desktop.

4. Open Mail and set it up again from scratch. If given the option to import existing mailboxes or something like that, don’t. Just enter the account information and check that everything works fine. Be sure to turn OFF Store messages on the server for all the mailboxes and all the AOL accounts in Preferences > Accounts > Mailbox Behaviors.

5. You’ll have to re-configure all your settings in Mail > Preferences. For spam-related security reasons, the first thing you should do is go to Preferences > Viewing and disable Display remote images in HTML messages if it’s enabled.

6. If Mail works fine now and you had any messages stored in local mailboxes, do File > Import Mailboxes, choose Mail for Mac OS X as the data format, and follow the instructions to import your mail from the old Mail folder that’s now on the Desktop.

Given how ~/Library/Mail/Mailboxes/ is organized in your case, I suggest moving the “On My Mac” folder out of there (e.g. to the Desktop), then separately import the resulting “Mailboxes” and “On My Mac” folders.

If all is well and you don’t miss anything, the files on the Desktop can be deleted, although you may want to keep them for a while, just in case.

Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder. You can easily locate any of the folders referred to in this post by copying the folder path here, doing Go > Go to Folder in the Finder, and pasting the folder path there.