EmailForwardMX uses a mix of common blacklists and advanced spam filtering, to prevent the forwarding of spam emails.
These spam filters cannot be disabled or turned off.
The reason that we cannot disable the spam filter is that all of the forwarded emails are seen as coming from our IPs when we forward them. Therefore, if a lot of spam emails are forwarded, most providers will start to blacklist our IPs as they are seen as the source of the spam, and all of our customer's forwarded emails will end up in their spam folders.
The same also applies for the reputation of your domain. During the email forwarding process, the email envelope is rewritten to come from your domain, instead of the original sender domain. This is due to SPF, because our IPs are not included in the allowed IPs on the original sender's SPF records. As a result, it could also result in your email forwarding domain being blacklisted as well if we allowed all emails to be forwarded on.
