Again, due to the robustness principle, just because a host does not define MX records does not mean they can't accept mail.
Mail servers will often fall-back to A records to try and deliver mail.
Here's what that looks like in the jquery demo app [source] we mentioned above.
0.0.12 from a previous version, you will need to make minor changes in your code. You can use it stand alone with the email-verify command and as many email addresses as you want to check.
So while an address like, "John Smith"@is completely syntactically valid, it does not actually exist at Yahoo Mail and will bounce.
That's why if we know the Mail Exchanger the mail is going to, and we know the big ones like Yahoo, Google, Microsoft (including Hotmail), AOL, and Apple we validate against their more stringent rules. Instead of @yahoo.com, you might type @yaho.com, that's why, as part of our validation service, if we detect a misspelled word, we offer suggestions so you don't miss mail due to a typo.
Email validation is a hard problem that every single developer, building anything on the web, has to deal with.
We actually have been working on email validation ourselves for years (more on that below).
Other options supported are -p The FDQN is used on the first HELO of the SMTP protocol.
Defaults for the sender are [email protected] default for the FDQN is mail.
We're launching this as a free service that anyone collecting email through web forms can (and should! You'll need a Mailgun account to use the service, but you don't have to send your emails through Mailgun.
If you want to get started right away, check out the API documentation, or a little sample jquery app, as an example of how to use Guardpost in a signup form.
We looked at the validation services available and weren't satisfied with any of them, either for performance, accuracy or completeness reasons.