Validating mx record
Once those caches are expired, they are dropped and the next time your entry is resolved, you will see the correct result.
This is why when you test a domain you’ve used recently, it seems to show old information even after an update.
get as far as ) to know if the server was likely to accept your message.
If there are multiple MX records, you would have to test all the servers until you got one that looked good.
Even if you are an anonymous user, you are given some credits to spend. Accounts of registered users have higher Daily Credits amounts and can even increase them by purchasing subscriptions.
Every IP address has its own account and it is provided with free credits that can be used to pay for Online Domain Tools services. Besides Daily Credits, all accounts, including IP address accounts of anonymous users, have their credit Wallet.
Now, there are other factors that take part in this.
For instance, DO batches updates to their name servers, so it may take a few minutes before they actually start responding with your latest zone.
This is pretty much all I can say, since you didn’t give us anything we can test with like the domain name.
Or is there a possibility that there exists a server that hides their MX record and even if email will be valid, check will fail. With some more research I have found that some servers use something like MTA for mail exchange which don't use MX record.
I know and I've tested that only emails domain is checked, not the user part. If I check A/AAAA records then, will that be enough?
If more servers have the same value set, the client should randomly determine their order.
The TTL value specifies how long the MX record stays valid.