In my case I never touched any data or meta-data files while Mail was operating. Other similarly simple interactions with the Mail UI Dragging a message to move it to a 'mailbox' (Apple's amusing term for sub-folder)ĥ. Double-clicking a message in the header pane to open the message in a new windowģ. Clicking a message in the message header paneĢ. I specifically saw the problem occur after doing things as simple as:ġ.

When Mail works it works fine even with large messages. I try not to go higher than that a popular mail services (Google, Yahoo, etc.) limit at 50MB. But if you click the message, let it display and then delete it, I think you'll be I regularly CC myself on mail messages with photos. So sometimes Mail is consuming 45% - 80% of CPU for about 3 to 5 seconds. I noticed that the problem has not occurred since I now wait to let messages load. So, upon start up, it has some invalid pointer or invalid state of the meta-data files. I suspect that Mail does not properly 'lock' the file so the index thinks the message is in your inbox but it's really not. If you try to delete the message too quickly or move it to another folder ('mailbox' in Apple's obtuse terminology) it might be causing this problem. I noticed that sometimes, a mail message appears in the message header pane but the message has not completed loading from the server (I suspect but cannot verify).

I suspect there is some race condition (some concurrency bug) in the software. By the way, I have reported this to Apple many, many times.

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