Although we strongly recommend enabling Junk Filtering on your webmail, you can turn it off on your webmail's settings.
Please note that after turning off this option, you might receive a lot of unwanted spam mails in your Inbox.
1. Login to your email account.
2. Go to: [Email] → [Configuration] → [Junk Settings].
3. Uncheck the checkbox for [Junk Mail filtering enable].
4. Click [Update] to save your configuration.