If it continues to, you could try deleting and recreating the account. Before you do that, select the account in Mail’s Mailboxes list, hold down the Control key, and click on the account’s Inbox. Choose Archive Mailbox from the menu that appears and choose a place to save your archive when prompted. Doing this ensures that the messages for the account aren’t completely vaporized when you delete the account. Ditto for the account’s Sent messages if you like to keep such things.
Now choose Mail > Preferences > Accounts, select the troublesome account in the Accounts list, and click the minus-sign (–) button to delete the account. Click the plus-sign (+) button and recreate the account.
My junk filter in Mail isn’t working; I keep getting spam, even when I mark a message as junk.
If you’ve studiously taught Mail what is and isn’t junk but it’s not learning, reset Mail’s junk-mail settings by opening Mail’s Preferences, clicking the Junk Mail tab, and then clicking the Reset button.
To begin anew, in this same Junk Mail window select the Enable Junk Mail Filtering option. As you’re just starting out, enable the Mark As Junk Mail But Leave It In My Inbox option. With this option on, messages that Mail believes are junk will be marked in brown. By leaving them in your inbox, you can first see if the junk mail filter is working and then identify mail marked as junk.
Scan your inbox and verify that what Mail is calling junk really is junk. If it isn’t, highlight the good messages and click the Not Junk button in Mail’s toolbar. Look for messages that are junk but haven’t been marked as such; if you find one, highlight it and click the Junk button in Mail’s toolbar. Over time, Mail will “learn” to better pinpoint junk messages. Once it’s learned to identify junk mail to your satisfaction, go back to the Junk Mail preferences tab and enable the Move It To The Junk Mailbox option. Mail will then automatically move mail it has identified as junk to a Junk folder (under On My Mac in the Mailboxes pane).
If you have a severe junk-mail problem that Mail can’t deal with, get C-Command Software’s $30 SpamSieve —the most effective spam-filtering tool I’ve ever used.
Bonus tip: You can transfer Mail’s junk-mail filter to another Mac, so you don’t have to retrain Mail on a new Mac. Locate LSMMap2 in youruserfolder/Library/Mail, and transfer it to the same location on the other Mac (replacing that Mac’s copy). Mail’s filtering on that other Mac will then be just as effective as it is on the first.
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