How can I test if an email address is a spammer's?

I received a reply to my Craigslist post, with a gmail address in the email body. Craigslist uses some way to hide my email addresses, if I choose to reply directly. But I replied to the gmail address provided, and immediately got an email which I recognized as spam. At the same time, I regret having revealed my true email address.

Now I received another reply to my Craigslist post, with a different gmail address provided in it. I replied via Craigslist, and have not received anything yet. I wonder how I can test if the gmail address provided is spammer's?


  • If a spammer has taken over a valid gmail account, I'm not sure what you'd be able to do to test. – schroeder Nov 26 '14 at 20:46
  • e.g. does some website can do the test if I give the gmail account to it? – Tim Nov 26 '14 at 20:48
  • "Blacklists" are what you're looking for, but all the blacklists I know deal with domains, and not specific addresses. Addresses can change on a dime, and not worth tracking. – schroeder Nov 26 '14 at 20:51
  • Can I fake my email address to send a reply to the email address, just to receive what he/she will say? I don't want to reveal my true email address. – Tim Nov 26 '14 at 21:16
  • If you fake your address, you won't receive a reply (the spoofed address will). You might try short-lived email services for that. – schroeder Nov 26 '14 at 21:27

There have been experiments with mail services, where the recipient must complete a CAPTCHA before reading your message and revealing your true identity and e-mail address.

Google has had a "mailhide" API up and running for website developers, but I haven't looked into a way to be useful to end users.

To answer your question directly - unfortunately, I do not think there is a direct way of finding out whether an e-mail address is used by spammers or can be trusted. If you receive an e-mail and look up the headers and sender identity, then you can lookup their reputation based on IP address, domain SPF and other criteria, but it isn't a guarantee. That's probably one of the reasons why we have been having this cat-and-mouse game with spammers for years - reputation is based more or less on the domain name rather than the reputation of an individual e-mail account.

The trust domain for e-mails has typically been that if you are sending a message to an e-mail address, then you implicitly trust that the address is genuine, whereas the focus has been more or less on filtering the incoming messages (spam filters, junk mail folders, etc.). Maybe it's a great feature that we're missing in our e-mail clients and servers?

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