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CNAME flattening is a vendor feature that returns A and AAAA answers for your bare domain even though classic DNS does not allow a real CNAME at the apex. Some DNS providers look up the CDN target behind the scenes and answer with those addresses so HTTPS can work at example.com. LogicWeb cPanel DNS does not flatten, so you place A and AAAA on the apex yourself and keep MX and TXT there as ordinary records.
What flattening actually does
Flattening is not part of standard DNS. The provider resolves the target name, caches the addresses, and serves them when someone queries your zone apex. You still depend on their TTL and on a second lookup on their side. A real CNAME at a name owns that entire name, which is why mail breaks when a wizard publishes one at the apex. www may use a CNAME without that problem. The apex should stay on A and AAAA unless your DNS host documents flattening and still lets you keep MX and TXT on the same name.
What to use on LogicWeb cPanel DNS
On LogicWeb shared hosting DNS you do not get CNAME flattening. Put an A record on the apex for your origin address, and add AAAA if you serve IPv6. Point www at the CDN with a CNAME when the CDN asks for that pattern. Leave MX and TXT on the apex so mail and SPF stay attached to a real name. ALIAS and ANAME are other vendor labels for the same kind of synthesis elsewhere; they are not portable if you later export the zone to plain BIND-style records.
If a CDN wizard already broke mail
Delete any CNAME at the apex, wait out the old TTL, and confirm that dig example.com CNAME returns no answer. Restore A and AAAA at the apex to your origin, or to whatever address your control panel shows when flattening is a real, documented option. Keep the www CNAME if the CDN still needs it. ACME HTTP-01 checks can also behave oddly when traffic lands on an anycast pool you do not control, so an explicit apex address is the safer path here.
When mail is working again and you only need to sort priority values, see MX priority, without folklore.
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