Got this post from somewhere about an efficient email tracking... Maybe it helps to those who are looking for a service like it.
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MailTracking stands out among several email tracking services by offering several sending options.
Most email tracking services offer "return receipt" back to the sender once the email gets read by the recipient. MailTracking does more than that by giving you several options.
These options include email certification that digitally sign your email and insert a timestamps certificate making it as court admissible evidence.
MailTracking allows your email sent to self-destruct at a predetermined time by you or when the recipient tries to copy, forward and print your email.
Your email's recipient may be barred from copying or printing your email.
Another great option is the assurance that your mail stayed on the MailTracking server until accessed by your recipient and a ReadNotification is sent back to you.
You can even retract your email even before it is read by your recipient.
Only MailTracking provides you with these great features. You can try MailTracking for free @
http://www.mailtracking.com/.