Understand what your scan results mean / MX
MX records explained: how email actually gets routed to you
An MX record is what tells the entire internet which server should receive email for your domain. Get the priority values wrong, or leave a stale one in place, and mail either fails silently or goes to the wrong place.
MX (Mail Exchange) records are DNS records that list the mail servers responsible for accepting email on behalf of a domain, each with a priority number. When another mail server wants to deliver email to you, it looks up your domain's MX records and tries the lowest-priority-number server first.
Multiple MX records exist for redundancy: if the primary (lowest number) server is unreachable, the sending server falls back to the next one. A domain with only one MX record has no fallback — if that single server has an outage, incoming mail queues up (usually retried for a few days) or eventually bounces, depending on the sender's own retry policy.
A common real-world mistake: migrating email providers (e.g. moving to Google Workspace or Microsoft 365) and leaving the old provider's MX record in place alongside the new one. Depending on the priority values, this can mean some mail still routes to a mailbox nobody is checking anymore — mail that looks "delivered" from the sender's side but is invisible to you.
What to do: after any email provider migration, verify only the new provider's MX records are present — Korantix's provider detection (Microsoft 365 / Google Workspace / etc.) is read directly from your live MX records, so a stale record here shows up immediately as an unexpected or duplicate provider match.