SpamHero can only filter email that it sees. Here are some common reasons spam might not go through the filter and what you can do to fix each issue:
If you have more than one domain name (aka Domain Aliases), and the other domains are not set up to go through SpamHero, all spam that is sent to you through these domain aliases will go straight to your mail server without filtering. To fix this issue, we offer free filtering for domain aliases. You can add them through the SpamHero control panel by going to Settings > domain aliases. After you have added them there, you will need to switch the MX records over as well.
If you added our MX records but left your existing one in place, you may see some spam coming through without filtering. Even if the priority of your MX record is a higher number (which is supposed to tell mail servers to only send to your mail server as a last resort), some spammers will sometimes send their spam to all hosts listed in the MX records. Some hosting providers require that you leave their MX record in place (in those cases, set the priority of the record to 50 or something higher). See the Hosting Providers Requiring Special Attention article if you are unsure whether your host allows you to remove their default MX record.
If one of your domain's email users has device that is infected with a virus, that virus will be able to send spam from your mail server. Since email sent from your own mail server doesn't go through our filter, the spam gets delivered straight to your email boxes. There are several freely available virus scanners that should allow you resolve this issue.
If you have a contact form on your website that allows people to contact you, it can also be used by spammers to send you spam that would not go through our filter. To reduce the amount of spam sent through your contact forms, add a CAPTCHA feature to the form to block bots from filling out your form.
SpamHero has a whitelisting feature that allows you to specify that a sender's emails should not be filtered. If you have whitelisted a sender that often gets forged (e.g. PayPal.com, ups.com, etc.) spam coming from these sources would no longer be filtered. To remove a whitelisting that is causing you to receive spam, go to Settings > approved senders and remove the email address that you are receiving spam from.
If spammers are sending directly to your server's IP address and ignoring the MX records for your domain, those emails will not be filtered. If that is happening, we have ideas on how you can secure your mail server here: Prevent spam from being sent to your server's IP