What is MX validation?
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Here's a quick reality check. If a domain doesn't have mail servers set up, you can't deliver email to it. That's what MX validation checks for.
MX stands for Mail Exchange. These are DNS records that tell the internet which servers can receive email for a domain. Every domain that accepts mail has MX records. Without them, mail just bounces. It's like having a building with no mailroom.
When you validate an email address, the validation vendor checks whether the domain has at least one valid MX record pointing to an active mail server. That's a basic sanity check. If MX records are missing or broken, the address is dead on arrival.
Here's the thing. MX validation is fast and cheap because it's just a DNS lookup. But it's also limited. It tells you whether the domain accepts mail. It doesn't tell you whether the specific address exists on that server. That's why MX checks are usually the first step in a multi-layered validation strategy.
Most email validators do MX checks first, then move to SMTP checks if the MX records pass. The combination gives you much better accuracy than MX alone. If you're evaluating a validation vendor, ask whether they do both.
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