How can I effectively block spam emails on my iMac?

Niku wrote:

Forwarding junk/spam mail to JUNK does not work for me. What are some other ways to block unwanted mail?

Start here:

Reduce junk mail in Mail on Mac - Apple Support

There is an app called Spam Sieve that does a good job filtering if you're willing to pay.

https://c-command.com/spamsieve/

Beyond setting up automatic filtering, there really isn't much you can do. You can stop using the email address that's getting all the spam and start using a new one. But that's really only kicking the can down the road. Eventually, you'll have the same problem with the new address.

Niku wrote:

Forwarding junk/spam mail to JUNK does not work for me. What are some other ways to block unwanted mail?

[Re-Titled by Moderator]

You can log into your email provider's web page and check if they offer server-level spam filtering as an option.

Installing SpamSieve got more complicated over time, as Apple added more layers of security for Mail plug-ins. However, with SpamSieve 3 and macOS 13 and later, SpamSieve no longer needs to install a plug-in, so the initial installation is simpler and there are no longer any extra steps required to re-enable it after each update.

That said, please contact me if you’re having trouble with install/setup. I’m happy to help.

[Edited by Moderator]

Niku wrote:

Thanks. I once used SpamSieve, but I discontinued it for an unremembered reason; however, I was just talking to Apple, and was walked through the UNSUBSCRIBE method. I had stopped using it, too, but he showed me ways to get to the same place (As you know, SPAM senders don't usually include an UNSUBSCRIBE button, though it is required by law.)

In other words, there is a way to add an UNSUBSCRIBE button even though the SPAM didn't include one when sent. (4/30/25)

There is no "UNSUBSCRIBE method" for decreasing or preventing spam. Legitimate commercial emails will have an "Unsubscribe" button/link. You should periodically go through the commercial emails you're receiving and unsubscribe from the ones you no longer want to receive. But that won't affect spam.

You can't politely tell spammers not to send you more spam. 1)They don't care, and 2) there will always be a thousand more spammers out there. Also, they frequently use fake email addresses so even if you asked them to stop, they wouldn't get the email.

Niku wrote:

Thanks. I once used SpamSieve, but I discontinued it for an unremembered reason; however, I was just talking to Apple, and was walked through the UNSUBSCRIBE method. I had stopped using it, too, but he showed me ways to get to the same place (As you know, SPAM senders don't usually include an UNSUBSCRIBE button, though it is required by law.)

In other words, there is a way to add an UNSUBSCRIBE button even though the SPAM didn't include one when sent. (4/30/25)

If you are using an "unsubscribe" button included in spam email all you are doing is verifying to the spammer that they have reached a valid email address. They then increase the amount of spam you get and they will sell your valid email address to other spammers thereby increasing the amount of spam you will receive.

Filtering spam, whether you do it manually, or by using rules in your mail app, or by using an app like Spam Sieve, is complicated. There's just no way around that. It's also never-ending.

michaeltsai is the developer of Spam Sieve. Apparently, Apple didn't like the contact information he posted. But it should be available on the website I linked to above.

He's very responsive.