How can I tell if the other person has received my email?

I am with yahoo email and received two emails from someone the second was sent because the person forgot to pu?

• forgot to put final line on first email so they emailed the second email which had final line on it; i am trying to add final line to first email and submitted question about this to yahoo questions people helped and said to open up first email and forward it to myself and when it was in forward then i could edit it so i added second line to first email but the second part disappeared when i received opened and checked forwarded email to my self, so i tried again this time forwarded it to my brother and asked him to send it back which he did; this time the second line was on it but the two attachments at the top of the page were gone could anyone help please if you can thank you for your time

• Answer:

  I answered that first question for you.----Let's try it again. As I said before: You can edit anything you want to, in an email that you have received-----BUT ONLY after you have clicked on "Forward". When you click on forward it puts that email into an "active" window (which is your composing screen) where you can (BEFORE SENDING IT) delete things from it (such as previous addresses or names)----OR add things to it wherever it's needed. AFTER you have made the changes you want---THEN SEND it to yourself. When you get the email--(that you have sent to yourself)--in your inbox, it will have all the changes in it that you have made. The ORIGINAL email that you got from your friend--WON'T be changed (that's impossible)----ONLY the email you sent yourself will reflect the difference. You say the attachments are gone from the sent mail when you got it back? Well that means you (or your brother) deleted them while they were in the forward window. The attachments WILL STILL be on the original email (from your friend). Good luck.