How to Fix Mail Memory Leak in macOS Sequoia 15.x
The Mail app in macOS Sequoia can occasionally balloon in memory usage, consuming 10GB+ of RAM and slowing down your system.
The full fix is in The Fix section below. Verified on macOS Sequoia 15.x.
Recommended Troubleshooting Tool
Before proceeding with manual fixes, we recommend using CleanMyMac X. Quickly identify high CPU apps and optimize system memory with one click.
The Symptom
Activity Monitor shows Mail or MailPersistence using an absurd amount of "Memory," and the system feels sluggish.
The Fix
- Disable AI Smart Categorization
The new AI sorting features are often the cause of the leak.
Go to Mail > Settings > Viewing.
Uncheck "Enable Smart Categorization."
- Rebuild the Envelope Index
Force Mail to re-index your messages without downloading them again:
Quit Mail. In Terminal, run:
rm -rf ~/Library/Mail/V10/MailData/Envelope\ Index*
(Note: Replace V10 with your current version folder, usually the highest number.)
- Limit Attachment Downloads
Go to Mail > Settings > Accounts > [Your Account] > Account Information.
Set "Download Attachments" to Recent or None.
Pro Tip
If Mail is completely frozen, use Command+Option+Esc to Force Quit before running the Terminal commands.