Re: "No settings for Mail's On My Mac Trash folder?
In macOS Mail, is there no setting to erase deleted messages from the "On My Mac" Trash folder"
For MacOS 15: Change Mailbox Behaviors settings in Mail on Mac - Apple Support
(Else: If you have upgraded to MacOS 26: Pleas choose correct OS at top of linked article for accurate info.)
Eg: says:
"Use Mailbox Behaviors settings in Mail to change where draft, sent, junk, deleted and archived messages for an email account are stored.
To change these settings in the Mail app on your Mac,
choose Mail > Settings, click Accounts, then click Mailbox Behaviours.
Note: Mail stores messages in the mailbox you specify for each option.
- If you select a mailbox on the mail server, the messages are available when you use your email account on another computer. Mail selects the best mailbox for your account; before choosing a different server mailbox, check with your email account provider.
- If you select an On My Mac mailbox, the messages are stored on your Mac and are available only there.
The settings shown vary depending on your account type."
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"Option: Trash Mailbox:
Choose a mailbox on the mail server or on your Mac to store deleted messages, or choose None (deleted messages are removed and aren’t available in the Bin mailbox).This option is available only for IMAP accounts."
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"Optiion: Erase deleted messages:
Choose when you want Mail to erase deleted messages.
To avoid exceeding storage limits set by your email account provider, choose a setting other than Never."
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Else if the settings above are not working for you, you may want to send feedback to Apple:
Apple's Feedback website: Product Feedback - Apple