Everyone seems to be relying on email these days. Use for personal or business dealings, just how reliable is email delivery system ? How do you make sure your email reaches the intended recipient/s ? You can use the "Return Receipts" feature which comes with certain email client system, however, this feature will not work everytime, as the availability of such feature is depending on the recipients email server configurations.
Call the recipients each time you sent a mail to confirm whether they received it ? What if you are sending to 100 recipients ? How many calls you going to make ? With email, its meant to cut down on telecommunication costs, so this measure will not served its purpose.
So the best way is to return back a mail to the sender, acknowledged receipt of the mail. It's not that hard or difficult to do. How much time will you waste by just replying, "OK, received. TQ".
Of course, you only do this if the mail/s are important or the sender requesting you to do so.
So if you are a sender & you want to be very sure that the email actually reaches the other party, put a small note requesting an acknowledged receipt. Better be safe than sorry.