It's been years since I've posted one of my opiniion pieces, but this one annoyed me enough to write about it. On 22 September, CircleID posted "100K+ List of Disposable Email Domains Under Security Analysis". I dislike the post as it is (in a technical sense) a poorly written/researched piece. A more accurate title would use "Marketing" instead of "Security".
Issues that I have with the "article" follow. Note: I use "article" in place of "ad" because, as an advertisement, the "article" is even more of a disappointment.
1) CircleID notes that it's a sponsored post. This means that someone is trying to sell/promote something. A minor bit of research will reveal that the "author" of the article is willing to sell you access to their list. I originally subscribed to CircleID's RSS feed because they posted about some of the ICANN level politics and issues relating to management of DNS domains. I've now moved CircleID to my "probationary" list.
2) There's no personal attribution for the article (unless someone legally changed their name to "WhoisXML API").
3) The article avoids discussing the benefits of using disposable email. Not everyone considers becoming a "key email marketing metric" a goal in life. Most consider "key email metrics" as an "unwanted commodity" (i.e., being added to marketing lists that are sold and resold). Notice that I'm being nice here and not using the pronoun made famous by Monty Python?
4) There is an unsupported claim that email security solutions can further be strenghtened by filtering out disposable email solutions. This is true only if you consider "key email marketing metrics" as having value. Legitimate email domains aren't immune to email blackholes. Example: someone going to a conference might give out a "temporary email address" (in their corporate domain) that ceases to exist a few weeks after the conference closes. Justification: avoidance of extended bouts of unwanted emails.
5) The list of categories that "stood out" seems a bit selective, in that ignores the primary use case for disposable email addresses. In short, they're disposable (i.e., it's used for one specific purpose and is allowed to expire). This ignored category is used to:
- acquire vendor's marketing fluff without becoming a "key email marketing metric"
- acquire other information without becoming a "key email marketging metric"
- enter in-person contests for $5 coffee mugs or sticker sets without becoming a "key email marketing metric"
- fill out "surveys" without becoming a "key email marketing metric"
- acquisition of other low value offerings, without becoming a "key email marketing metric"
Do you sense a common theme here? I do.
6) The hidden author's math is extremely weak. From the article: "We analyzed one such a list which, as of 31 July 2020, contained 109,352 disposable email domains. This is enough to create millions of throwaway email addresses."
Given a single email domain, over a million email addresses can be generated from a four character username limitation (a-z and 0-9, with omission of any special characters). If you do the math (36 x 36 x 36 x 36) it comes to 1,679,616 "words" that you can put on the left-hand side of the "@".
Using that same 4-character limitation on the "researched" 109,352 suspect domains, the math allows you to generate 183,669,368,832 (almost 2e+11) email accounts. That's just a little bit more that "millions of throwaway email addresses".
Bumping the username side of the email address to 6 characters results in over 2e+14 email addresses (more accurately in the 238,035,500,000,000 ballpark). Imagine what you can do with 12 or 16 character usernames!
7) WhoisXMLAPI's pricing appears a bit steep, too. For just my email adddress (a single user account in a single domain), on 23 September, I received 11 emails that the system deemed "unsolicited" and another 22 for which I wish I'd used a disposable email address. If you consider that "normal" and expand it out to a 30-day month, that's 990 undesired emails, 660 of which I have to delete manually. WhoisXMLAPI's "free" service has an upper limit of 500 queries. The next tier up allows for 2000 queries per month, at a $15/month rate. If I have two employees, that bumps me into the next tier, at $30/month.
If the query resuls are delivered via a DNS-based service, this is extremely expensive (2000 queries per month for $15?). If they're reselling information that is free, elsewhere on the Internet (SORBS, Spamcop, etc.), I have more reasons to dislike them.
I don't like their pricing plan either. They have you buy credits, which you can use in a single month. I you don't use the credits, they expire and you no longer have them. It's not their fault if you overestimate your spam load for the coming month. While this minimizes their need for customer interaction, it maximizes yours (if you worry about costs). A simple metering system would be more customer friendly.
I'd much rather worry about my own domain ending up on an email blacklist. For that, I can perform the RBL lookups myself (with a bit of code), perform those same lookups via a free web site (e.g., DNSWatch), or have someone monitor my domain (e.g., MXToolBox), all for free.
Overall, I think the article was aimed at the non-technical CIO, CSO, or CTO (yes, they do exist). The primary sales tactic seems to be the old-standby: be afraid, be very afraid. It's a bit disappointing that CircleID is promoting this stuff vice their own articles, many of which caused me to subscribe to their RSS feed years ago.