So you know that people don't like receiving personalized messages that are tracked and yet you are proud that you have devised a way to shovel them down their throats anyways. Good stuff.
(edit) I would've not minded if this were purely technical post on how you set things up, but the way its edited at the moment just reeks of disrespect towards those on a receiving end of your emails.
If you simply receive an email and read it, and the sender can glean the same information, that is something entirely different.
"Oh, but everyone does it, so it's ok right?"
I know this is unlikely, but sending an email that looks like each party is getting the same thing but in fact are getting different emails just is bad.
The tracking thing is not a big deal, seems like everyone does it. Just block images and you are golden.
You're entirely correct that this part of the SMTP spec does potentially allow for dubious behavior -- and that's one of the reasons I wanted to publish this article. I have a feeling this is one of the little-known secrets of email sending which we should all be aware of.
EDIT: Also, I'd like to point one that the real textual content of a message can't differ when sending through Close.io so the scenario you explained above isn't possible within our app.
None of my email clients, on OS X, Windows, or Linux, will show that pixel unless I press a button or take some action.
And I believe that is increasingly the default behavior of email clients, isn't it? Which means this technique will increasingly not work, and there is nothing close.io can do about it.
> scummy and uninteresting business model
We make a sales communicate platform that integrates CRM + calling + email. <sarcasm> You're right, it is a pretty uninteresting business model in that we don't use some new-fangled financial instruments to cook our books -- it's just boring ole' monthly recurring revenue at a SaaS company. </sarcasm>
Scummy? Don't even know where to begin on that one -- but if you're in the Bay Area ping me. I'd be happy to sit down and entertain any ideas you may have that we run a scummy outfit. Seriously. I really would like to understand the context behind that statement. It's not something I take lightly as a founder.
> None of my email clients, on OS X, Windows, or Linux, will show that pixel unless I press a button or take some action.
Yes and no. You can set most clients to load images by default -- I haven't tested the default settings on all clients so I can't speak about what percentage that accounts for. I'd assume someone like Mailchimp/Marketo/Pardot/etc. may have published some interesting findings about this.
You're entirely right, however -- we can't do anything if a client blocks images. And that's OK. Tracking is a feature our customers love being able to utilize when they can, but they also understand that it's not entirely accurate.
Surreptitiously tracking users without their knowledge or consent (and I mean the end users, not your users who are paying you to do it) just isn't something cool to brag about, any more than robocalling people at dinner, or a thousand other things that are nevertheless legal and make monthly recurring revenue for those who do them.
Not saying you shouldn't be able to do it; a lot of unseemly and faintly repulsive things happen in the name of marketing. I'm just saying it's kind of a lame thing to do in general, and it is pretty off-putting to read a blog post that basically says, "Look how rad we are for tricking all these people and tracking them without their knowledge!"
Oh, but everyone does it, so it's ok right?
And to address the: 'I don't get the "without their knowledge or permission" part.' - What don't you get about this? The recipient doesn't realise the tracking is taking place, and the sender never asked permission to perform the tracking, nor to store the data...
> the sender never asked permission to perform the tracking, nor to store the data
Well, in this case the sender would be someone using Close.io as their CRM. So they actually almost certainly do want this tracking to be performed.
SMTP and IMAP are transport protocols. For transporting text around:
"By utilizing SMTPs RCPT TO command" - He's not utilising anything special. This is exactly how every other email that employs tracking pixels is sent. A separate recipient and message body for each recipient.
"Remove any messages stored by the SMTP server" ... "Google's SMTP servers store a copy of every message"
Nope. SMTP is used for mail servers to pass email about. An SMTP server doesn't store mail, apart from in it's temporary queue before forwarding it on.
"Store sent mail in IMAP" ... "If using a service like Gmail which stores all sent messages automatically in IMAP" - Again, you don't store email in a message transfer protocol.
This article reads particularly badly because of the repeated incorrect use of terminology.
 And to address your comment, "they actually almost certainly do want this tracking to be performed" - "want" is an interesting word to use there. If there was a tick box in the top right corner of peoples email clients which said:
Allow senders to track when you open a message,
where you were when you opened it, and various
pieces of information about your system
Note that Google's SMTP servers do store the messages in your sent mail folder. I don't claim to know exactly how they do this (IMAP, direct access to filesystems, whatever), but the messages are stored -- and yes, obviously the SMTP protocol doesn't facilitate this but their SMTP servers perform this action.
Asking whether this is morally/ethically OK is probably not the right question. As we've seen with any technology, if something is possible to track/store/analyze it will be. If tracking email opens (or any data on the internet) is not something we want to accept as a society we need to find ways to ensure tracking those actions under any circumstances is impossible -- not just leave it up to chance.
"morally/ethically OK is probably not the right question"