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I am building an app for Mac OS X that brings in email addresses from an Excel file.

Is there any method in the SDK that would allow me to check if an email is valid, e.g. a Hard Bounce? Something similar to using ping but for emails?

Nic Hubbard
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    Nope. Or, at least, if there is, there shouldn't be. Any sane SMTP server won't tell you whether an e-mail actually maps to an account, or you'd be able to use that functionality to brute force a listing of the user accounts. So, in practice, this 'ping' functionality wouldn't be helpful. – Parthian Shot Feb 13 '15 at 00:07
  • I have seen some online services that do this. They must be using some network method to check the response... – Nic Hubbard Feb 13 '15 at 00:08
  • @ParthianShot - True. I guess I am just looking for something similar to getting a Hard bounce in Mailchimp or other bulk mail senders. But, I am assuming that can only happen if you try sending them mail. – Nic Hubbard Feb 13 '15 at 00:09
  • Are you sure they aren't just checking that the format of the e-mail address is valid, and there's an SMTP server listening for the domain (by doing a DNS query for an MX record)? That seems like the easiest reasonable thing to do, short of actually sending an e-mail. – Parthian Shot Feb 13 '15 at 00:09
  • @ParthianShot - I am not sure. It looks like they are not very reliable. – Nic Hubbard Feb 13 '15 at 00:12

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No, there is not.

The only way to test if an email address will bounce is to try sending it an email and see if it bounces. It isn't possible to do this directly from most desktop computers, as most residential ISPs block outbound SMTP, and there is no method in the Mac OS X frameworks to do so.

  • Worth noting that testing e-mail addresses this way can get your mailserver's IP blacklisted. So, you want to make sure **most** of the mail you're sending is to actual people, and you definitely want to make sure you don't use lists of e-mail addresses slurped from the internet (partly because that's illegal, partly because those lists sometimes contain addresses that only exist to help identify spammers). – Parthian Shot Mar 01 '17 at 06:07