— I think the only thing you can do to validate an email before you send and actual email is to validate the “correctness” of the email. With like regex or similar.
The npm package isjs have an email regex validator. If you only use that maybe you can search the source code and copy that function only.
— But if you want to know if an email was delivered, dropped or flagged as spam, SendGrid have some awesome insights. I’m unaware if other services do something similar.
— Actually, the protocols support asking the mailserver
— So you can with reasonable accuracy do it
— But the question is; why not just send an email?
— Sendgrid is free ?
— No; it has a free month limit, but in production it will not enough. So it’s not free.
— If i send thru gmail, can we know the result ?
— I think not. But I’m not actually sure.
— If you are gonna use the Google GMail API you have to know that is very limited for a normal gmail account. And you have to pay a GSuit account if your plans include to launch something to production.
It’s not the approach I would choose.
The other thing you can do to validate an email and check if the recipient is the actual user is to actually send a email with a link and a message with the reason of the link, advertising that if he/she didn’t request that link is better not to open.