Sender Policy Framework (SPF) is an open standard that senders can use to publish which IPs are authorized to send email from their domain. There seems to be some confusion about the difference between having an SPF filter enabled for your domain and having an SPF record for your domain.  These are two different things. 

An SPF record is a special DNS record that tells the world what IP addresses that your domain is allowed to send email from.

An SPF filter is something that can be enabled on most mail servers.  It examines the SPF record of the envelope sender's domain and may block the message if the sender's IP is not listed in that domain's SPF record.

Having an SPF filter enabled for your domain is not recommended when you are using SpamHero as it may block domains that have SPF records from sending emails to your domain. If you are unable to shut off your SPF filter, you will need to enable our SPF workaround feature. Removing your SPF record does not disable your server's SPF filter, and is counterproductive.

Having a properly configured SPF record for your domain is encouraged. While it won't prevent scammers from impersonating your domain on its own, it can help improve the deliverability of your outbound emails.