What mail client?
If you are using something like Microsoft Outlook then you can request both DELIVERY and READ receipts.
The former is confirmation that it reached the destination server and was accepted, the latter is whether the recipient actually read or deleted it. The Delivery receipt cannot be stopped, as far as I know, whereas a user can set his own email client to ignore Read receipt requests, ask if they should be sent, or send automatically.
M H C
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