The short answer is "You can't".
The basic email protocol does not have any mechanism which requires acknowledgement of receipt built in to it, and once the email has left you, its no longer in your control, and (rightly imho), you do not get to dictate what can be done with it.
There are a few things which can be done which can confirm if an email has been read - however there is no requirement that the recipient do these things, so its a matter of "if they do these things you can confirm they have read it, but if they don't confirm, it does not mean they have not read it". These also require preparation BEFORE the email is sent, so won't help you unless you send another email (or did them before hand).
The first thing you can do is specify a "read receipt" request. When an email is opened it can send a notification to the sender confirming it has been read. Most applications will, however, prompt the recipient before sending t he confirmation. This mechanism uses the browser.
The alternative mechanism requires crafting an email with images (often, but not always a 1x1 clear pixel), with a unique name hosted on a web server. If and when the mail client opens the image, the web server can track that the image has been sent. This mechanism is often used by mailing lists - and, of-course, mail clients can be configured not to open off-site images or 1x1 images etc.
SMTP has had delivery status notifications since 1996. Sadly many servers still don't support it...
– user1686 – 2016-01-27T07:50:37.4301Largely agreed, RFC1894 this works at an MTA level and does not prove the user has opened it - in fact all references to user agents in the RFC talk about "allow", rather then "require". Section 4 (particularly 4) make this optional - and indeed, any provider who sends notifications for their client is breaching confidence (ie is illegal in some countries), and opening up their clients to spam. [ FWIW, I think its a GOOD thing that servers don't support it ] – davidgo – 2016-01-27T08:00:33.730
Hmm, where is delivery status illegal? Many post offices have certified/registered mail as an equivalent... (Read receipts are another thing of course. I'm not talking about those.) – user1686 – 2016-01-27T08:09:13.110
I live in New Zealand, and I would be extremely hesitant to allow this behaviour - even only on privacy grounds [but these are not even the primary grounds - I'm more worried about spam]. See http://www.legislation.govt.nz/act/public/1993/0028/latest/DLM296639.html Principle 4(b)(ii), Principle 5(a)(ii) and 5(a)(iii) and Part 9a for relevant NZ law. Australia has a similar act - https://www.comlaw.gov.au/Details/C2015C00598/Html/Text#_Toc437527218 part VIA from a quick reading, and I am pretty sure a lot of European countries have similar legislation.
– davidgo – 2016-01-27T08:14:05.8102Actually, on a closer reading of RFC1894 I take back most of what I said - this is low level stuff which talks about message delivery failures in a way which allows for catching of errors, rather then any kind of confirmation that the email has actually been delivered to a mailbox (let alone a read-receipt) – davidgo – 2016-01-27T08:20:00.330
Hmm, if the final SMTP server also gets a DSN request, I'm sure that should also cover delivery to the MDA... and if not, then most mail servers in practice do at least report about failed deliveries. (Of course, if it gets delivered to the "Spam" folder, it's still a successful delivery. But if the MDA couldn't store the message, that pretty much always causes a report...) – user1686 – 2016-01-27T08:29:02.067
Not at all, many mail servers I'm aware of will silently accept clear cases spam and drop it - no notifications of any sort - ie it doesn't even get delivered to a spam folder - and indeed if people are using POP, I can't see how a spam folder would even be useful to them ! – davidgo – 2016-01-27T08:35:11.137
As for legislation, at least Australia does have delivery receipts
– user1686 – 2016-01-27T08:37:01.157Agreed, physical email does offer delivery receipts (not read / parcel opening receipts) . I would also opine that this is to facilitate legal processes, and at a cost, and, crucially, between 2 parties with a presumed legitimate reason to be communicating with each other - which is very different to a spammer going on a fishing expedition - which would be a common use (and I fear that what the OP is doing may be very akin to spamming) – davidgo – 2016-01-27T08:42:32.093