SMTP Verification

Question

I hope this question is not completely off topic.

I was interested to learn about SMTP email checking. There are so many services (e.g. Kickbox.io, Email-Validator.net, etc.) that seem to handle SMTP checking without blocking their IP addresses or rejecting SMTP requests.

As far as I know, there is still no other way besides using the SMTP "VRFY" command, and to disconnect after the target SMTP server confirms the presence of the requested user on this mail server. I play with several PHP scripts that claim to do this, but I am rejected all the time by some mail servers, especially hotmail (like all other Microsoft mail services), it seems to reject SMTP Requests very quickly.

Now, my question is: how is it possible that services like the ones I mentioned above process thousands of email addresses per day and check them through what they call "SMTP handshakes" and do not see such problems, such as The ones I described?

Thanks for reading.

Answer 1

Companies such as Email-Validator.net, start by analyzing the email address to see if it is syntactically valid, whether it is legal and useful (for example, probably not a postmaster), whether the domain is valid (has valid DNS records ), regardless of whether the address is an outgoing e-mail service and other methods of checking whether they can immediately disqualify it.

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, , kickbox.io, , Microsoft Hotmail, , . , , . , , , .

Answer 2

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