I would like to ask if there is any way to ensure that my sent email was read, and to ensure also that the attached files were opened.
I use Hotmail.
No, this is impossible. There is no reliable way to know what happens to an email once it leaves your client. One technique for confirming an email is read is to include an html image tag (usually hidden) that references an image on a server in your control. If the image is opened, this means the email is opened. However, most email clients block the opening of remote images precisely for this reason - privacy takes precedence. So it does not ensure you are notified.
If this is a service you require, then the email would need to be sent using a service in your control.
One option would be something like SecureFTP. File are sent as links in an email, and to access the files they must log into the secure site (using their browser). If the files are downloaded, you are informed.
This might be a little too philosophical, but there's no way to ensure someone has actually read your email. Even the received/read notifications do not ensure this. Why? Because it is a simple question of not being able to read someone's mind. The notification ensures only that someone has seen that the message was received.
My way of dealing with this is asking for an answer when the other person has read and / or acknowledged the contents of my email.
SpyPig. Problem solved—free.
SpyPig is a simple email tracking system that sends you a notification by email when the recipient opens your message.
It works with virtually all modern email programs: Outlook, Eudora, Yahoo Email, Gmail, Hotmail, AOL Email and many others.
The most simple and common way to do this is using tracking images. Services such as Mailchimp provide this as part of their broadcasting service, and regular users can achieve it thorough services such as GetNotify.
The principle is you embed an image in the email, even a tiny 1x1px invisible thing. As soon as them image is pulled then that request is logged, and the URL to load the image is unique to that recipient of that email.
You can give it a go for free and it's the most reliable email tracker around.
They use many techniques (not just embedding images). Goodluck!
A trick I've always used if there are intended links for a recipient to visit is to shorten the links with a unique bit.ly url. Then I can track if the user clicks on that link in with bit.ly analytics.
Of course this fails if the email is text only, but perhaps it will solve some of your issues.