4 ms·

How sure are you that the 61 character limit won’t change in some future DNS improvements? People used to think TLDs would only ever be up to 3 characters long.

• chrismorgan 5y ago
  You seem unreasonably hostile. I’m absolutely certain that the 63-character limit for domain labels is never going to change, because it’s hardcoded in enormous amounts of software and hardware, and there’s no even vaguely compelling reason to even attempt to change it. But if such a thing did change, then you’d just add this to the extremely long list of things that needed to be updated. People who thought TLDs would only ever be up to three characters long were simply wrong from the very start because they didn’t understand what they were dealing with. (As a simple example, .arpa was there from the start.) Understand that this wasn’t a matter of anything changing, it was that some people misunderstood and thought that a convention they observed was in fact a rule. The problem this sort of validation is solving is weeding out things that are definitely not going to work, as soon as possible, because it’s good to point out problems to users as soon as possible, rather than having something silently fail or only notifying the user about it much later. Syntactic validation isn’t the be-all and end-all of accepting email addresses, but it’s definitely still worthwhile, even though you should generally do other validation based on DNS lookups and/or sending actual emails as well.