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How can you check if an IP is good or spammy? It would be nice to get an elastic IP in the cloud, test it for spamminess, and give back the bad ones. Catch and release fishing for IPs.

In practice, while there are some services which will purport to tell you an IP's reputation, their output isn't well correlated with actual delivery outcomes at scale (depending, to some extent, on what domains you're sending to).

This is because the big consumer mailbox providers often don't rely on public datasources for assessing reputation, and because reputation is tracked at the domain level, in addition to - or sometimes instead of - the IP level. For example, there have been some indications from Gmail that they no longer use IP reputation at all, starting a year or two ago.

And re: blacklists: +1 to Spamhaus, but in practice it's one of very few blacklists that have meaningful impact to net delivery.

> there have been some indications from Gmail that they no longer use IP reputation at all

I can believe it. I posted already about my experience with the free tier of Mailgun's service. I went through all their instructions about setting up the service and verifying my domain etc. but still had a lot of email rejected, especially by yahoo.com but also hotmail.com due to poor reputation IPs

Gmail.com typically delivered everything.

You can check the Spamhaus lists. It's a non-profit org dedicated to all-things-spam. https://www.spamhaus.org/

I found this service a few days ago to monitor our own deliverability. It allows you to test if your emails are delivered by the most common ESPs: https://glockapps.com

(I do not have anything to do with the product or team behind it)

Similar service here:


(I am likewise unaffiliated.)

Even so, this may not be very beneficial.

In years past, many RBLs would categorize IP Addresses by type. e.g. dynamic IPs assigned to DSL/Cable subscribers. This would enable a receving SMTP server to check if the email came from an ISP subscriber, rather than an email server. If so, it was usually a good guage that the email was "spammy", because it was sent by a subscriber's infected computer.

In this sense, it was (and may still be) possible to simply block, or at least score differently, email from any/all AWS Elasic IPs.

The term to search for is "RBL" (real time blacklist). Search for "check rbl" to find interactive sites, or maybe "check rbl github" for code that you can use yourself (though you may have to sign up for several services if you go that route).

Neither, though, helps with checking if one of the big providers, like Google, would not like your IP. For those, you have to send an email and watch/parse the SMTP error responses.

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