Prevent users from creating an account with invalid email

[Myrdrahl]

We're using SendGrid API to send emails, when users register a new account. We recently were contacted by a user who couldn't log in, and would not recieve emails when using the "forgot password" feature. After investigation we could see that they had made a typo when registering.

After checking the logs in SendGrid, we could see the following error:
"unable to get mx info: failed to get IPs from PTR record: lookup : unrecognized address"
This means that the user was able to create an account, without a valid email address.

If possible we would really like to see a hardening of this process, having the account creation process take into account the response from the SendGrid API, thus preventing users from creating accounts with email addresses that are not reachable.