The Apple Mail program included with OS X may develop corruption in the system settings and/or data files. This will cause the client not to receive all new messages on your POP mail server (your host). If you are using only a single computer to access a POP mail server, you may not even know that this problem exists. the problem is easily identified by using the web mail client to view your inbox online. If there are messages visible in your inbox when on the Internet, but those messages never show up on your desktop computer, then possibly the Apple Mail client is corrupted.
If you are using an iPhone, you may notice the problem because messages are being retrieved by your iPhone, but they aren’t showing up on the desktop computer (at least some of them aren’t showing up).
- Make sure the problem isn’t the result of messages going to a spam folder.
- Make sure that one of your computers isn’t configured to delete messages from the server after downloading.
- Ensure that the messages are indeed in the inbox on your mail server (host) by logging into webmail.
If you the problem seems to be related to the Apple Mail program (as described above) then follow the steps outlined below to correct the problem. These steps are generally described (for the advanced user) with smaller details left out.
- Create an archive folder in the Mail program that can hold any sent or received messages you’d like to save. The following steps will result in no mail or accounts remaining in your Mail program.
- Move all e-mail that you want saved into the archive folder (and sub folders) created in step #1 above.
- Exit the mail program and double click on the hard drive to view its contents then open Users > your folder > Library > find the Mail folder and copy it to a safe location such as an external drive. Find the preferences folder (in Library) and within there, find the com.apple.mail files (there may be only one of these) and copy it/them to your desktop or the safe location where you put the mail folder.
- Delete the Mail folder described in step #3 above and also the com.apple.mail files described in step #3 above.
- Start the Mail program again. It will not remember any previous accounts or settings. However, if you are a .Mac user, your .Mac email account may be automatically configured for you.
- Provide the POP account settings for your POP account server and then retrieve the email messages.
- The problem should be solved at this point since all previous corruption should be gone. From the File menu in the Mail program choose Import Mailboxes and navigate to the Mail folder you saved in step #3 above. Your saved archived messages will be imported back into the mail program.