If you are using external nameservers / DNS, then you will need to update your MX records to route incoming mail through our SpamExperts cluster.
There are some additional considerations you will need to take into account when configuring Cloudflare to use SpamExperts, which we have outlined/explained below.
When an account is enabled in SpamExperts, the 'downstream' server (which is the 'destination' for email delivery) is detected based on the 'MX Records' configured on the server, rather than those within your external DNS. In short, the SpamExperts solution will check local DNS records, rather than detecting the downstream automatically from Cloudflare, or other DNS providers.
The default MX records within a cPanel server will be to route to the 'domain' directly, such as the following...
MX 0 domain.tld
However, the consideration here is that in many cases, if using Cloudflare, 'domain.tld' may route via the Cloudflare 'Proxy' (the orange cloud in the Cloudflare interface), which masks the IP address of the destination server. Given that's the case, you will need to set the 'downstream' server manually through the SpamExperts interface to point to the hostname of the server directly.
The 'downstream' when using Cloudflare, should be the hostname of the server where your sites are hosted (this information will be in your welcome email). If you are using an external email provider, then SpamExperts likely isn't required - however, if you wish to benefit from the additional layer of filtering / protection, you can update the downstream to the correct MX / endpoint as per your provider's instructions.
Please note, that SpamExperts is an external cluster that works through a dedicated set of MX records. Once you have configured the steps above, you can update your MX records to the following...
mx1.spamfiltering.io mx2.spamfiltering.io
Once the MX records have been updated to the above, the emails inbound will be filtered by our SpamExperts cluster automatically, then routed 'downstream' to the server which hosts your accounts.
Please note: If your domains use external MX records, such as Gmail or Outlook, then you will need to ensure that your cPanel -> Email Routing is set to 'Remote Exchanger'