ReadNotify is an extremely sophisticated certified email service that has options to let you know whether an email you sent was opened under all circumstances and provides proof of your sending, too, while hiding most of the complexity behind easily accessible plug-ins, tools and email shortcuts.E-mailSecure is a highly flexible email return receipt service that lets you know when your messages are opened and can proof both email sending and opening. While E-mailSecure lets you exert considerable control over your messages, it does interfere with normal email workflow.pointofmail is a very comprehensive proof of receipt and reading service for email. Though easy to use, pointofmail can ensure read receipts, tracks attachments and lets you modify or delete sent messages. Unfortunately, working with pointofmail-certified mail can be cumbersome, and most pointofmail modes do not inform the recipient they are watched.<p>Confimax makes it easy to receive <a href="https://www.lifewire.com/request-read-receipt-outlook-1173448" data-inlink="3H6SL0OE5zkPdltGXVi4UA&#61;&#61;" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="1">return receipts</a> as soon as the recipient opens a messages. Unfortunately, these receipts aren&#39;t guaranteed</p>DidTheyReadIt makes it really easy to know if and when an email you sent was opened. Unfortunately, DidTheyReadIt is problematic as recipients have no idea their actions are recorded and there is no way to opt out of DidTheyReadIt return receipts.