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<?php $emailDomain = 'subdomain.example.co.uk'; $domainParts = explode('.', $emailDomain); // The TLD will never be in the allow list, so we can pop it off first $domain = array_pop($domainParts); $listToCheck = []; foreach (array_reverse($domainParts) as $domainPart) { $domain = $domainPart .'.'. $domain; $listToCheck[] = $domain; } var_dump($listToCheck);
Output for 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array(3) { [0]=> string(5) "co.uk" [1]=> string(13) "example.co.uk" [2]=> string(23) "subdomain.example.co.uk" }
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49.71 ms | 406 KiB | 5 Q