7.9 Does SpamSieve stop Web bugs?

A Web bug is a tracking image in an HTML-formatted e-mail message. The image is referenced on a remote server, rather than included as an attachment to the message. When a mail client displays the message, it loads the image from the remote server. When the server receives the request for the image data, it knows that the e-mail has been read, and it can record the address of the computer that requested the image. Additionally, the image’s URL may include tracking information such as your e-mail address, so the server can tell who read the e-mail.

Some legitimate mailing list providers use Web bugs to track how many of their messages were read, when they were read, and where (approximately) the recipients are located.

Spammers use Web bugs to track who is reading their messages. This lets them tell which e-mail addresses are valid as well as which variants of their message content get through spam filters. An e-mail address that is known to be valid is likely to receive more spam.

SpamSieve protects you against Web bugs by telling the mail program not to load remote images for messages that it thinks are spam. Since SpamSieve catches almost all spam messages, you only risk triggering a Web bug if SpamSieve lets a spam message through and you view that message. (If you know that a message is spam and don’t want to select it to train it as spam, you can train it from SpamSieve’s Log window use or the drone setup and drag the message to the TrainSpam mailbox.)

Note: On macOS 10.15 and macOS 11, SpamSieve does not tell Apple Mail to load remote images because this triggers a Mail bug that can prevent rules from moving messages to the proper mailbox.

For full protection, most mail clients have an option to disable the automatic loading of remote images for all messages, rather than just known spams. The downside to this approach is that to fully view a good message containing remote images you would need to click an extra button to tell the mail client to load the images.

Since SpamSieve is highly accurate, most users opt for the convenience of its automatic protection. If you want full protection and don’t mind manually loading the images for all your messages, follow the these instructions for your mail client:

Apple Mail

On macOS 12 and later, in the Settings window, click on the Privacy tab. Make sure that Block All Remote Content is checked.
On macOS 10.14 through macOS 11, in the Preferences window, click on the Viewing tab. Make sure that Load remote content in messages is unchecked.
On macOS 10.13 and earlier, in the Preference window, click on the Viewing tab. Make sure that Display remote images in HTML messages is unchecked.

Airmail

In the Settings window, click on the General tab. Make sure that Autoload Remote Images is unchecked.

GyazMail

In the Settings window, click on the Display tab. Make sure that Show remote images in HTML messages is unchecked.

MailMate

In the Settings window, click on the Security tab. Make sure that Image Blocking is checked and set to All Messages.

Mailsmith

Mailsmith does not display remote images, so no setting is necessary.

Outlook

In the Settings window, click on Reading. Make sure that Automatically download pictures from the Internet is set to Never.

Postbox

In the Preferences window, click on the Privacy tab. Make sure that Block loading of remote images in mail messages is checked.

PowerMail

In the Preferences window, click on HTML reader. Make sure that Download external pictures if connected, for non spam messages is unchecked.

You can use Email Privacy Tester to verify that remote content is not being loaded.