Wow, what did the CampaignMonitor folks eat? 
"Verifying emails is an email marketing best practice": guys, CONTEXT, please. 
Dropping catchy headlines like bombs is not making you any good. 
Then quoting someone about real-time verification in a part about "List decay" 
either his a badly orchestrated communication stunt, or pure stupidity.

> There *are* valid times to *validate* an email address in that manner
Yes, yes and yes. The only moment email validation is ok is real-time at the 
I've seen, to prevent typo domains, auto-completion or dropdown lists, first 
with most common domain names, then narrowing down to known domain names based 
on what the user it typing. No need to connect to anything to validate, here.
Then, to validate that the address is the right one, and that you're adding in 
your database the email address of the owner of the email address: confirmed 
It's as simple as that. No need to think any further.

To me the list-validators are dark grey hats. Their real-time service can be 
legit. The rest, I don't see how.


Benjamin Billon

-----Original Message-----
From: mailop [] On Behalf Of Stefano Bagnara
Sent: Wednesday, 7 March, 2018 17:13
To: mailop <>
Subject: Re: [mailop] Hat color of list washers / validators

On 2 March 2018 at 21:45, John Johnstone <> 
> [...]
> It seems somebody gave some fairly purposeful thought into coming up 
> with the algorithms to generate these.  I'm curious to know what 
> peoples thinking is as to the hat color of these attempts.  
> Particularly if there are any opinions on the risk / need to block them.

Tools like try to suggest you the "pattern" used by a company so that 
you can guess email address for named people, but they mainly use crawled data, 
so I think your suspect is
put a name and surname and your domain and it will try to guess the patterns 
and "verify" them.

That said, about the hat color....

We're a small ESP and I think email validators/cleaners are making OUR life 

We can identify bad clients/customers as soon as they load their list if it 
contains very old expired domains, spamtraps, fake domains, emails like 
"e...@ail.jpg" or some .pdf TLD. Or we can identify "non confirmed" lists 
because of the presence of many typos domains. This let us block and vet the 
senders BEFORE they abuse our tool (and send spam).

But if they come with a cleaned list then it is harder for us and we have to do 
the first send in order to understand they are spammer, and sometimes when they 
have mostly b2b addresses it is hard because of missing FBLs from the providers 
and very low feedback from recipients that know it is spam.

I think that from a receiving MTA point of view, this is the same: if they hit 
your spamtraps (or simply invalid recipients) you have more chance to deal with 
them "correctly" and early.

So, from our point of view, bulk list validators are bad and I can't see a 
valid point to use them, but trying to trick the game (for short term spamming 

That said, some ESP have a different opinion from me, as I just read this 
recent post:

I'm interested in how receivers see this email verification tools and how many 
of them deployed protections from them (e.g: identify their IPs and refuse or 
fake the answers to their requests or anything else).


PS: between the many email verification tools, Kickbox
( have a claim "Kickbox is a white hat service 

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