cannot receive "some" emails that have been sent back by reply

[#1]

Why is it that when my friends send me a reply to an email i have sent to them it is a delivery notification failure?
I have had to ask them what the address of my email is showing and its showing something like my name then mail @ then my name again it doesnt make sense but when i send them the correct email address i receive the email.  So i have had to send them an email from my second email address and there is no problem with it then! Has anyone had this problem

[#2]

Basically, this is your fault, you are sending the wrong information.  Your email settings include a record of your email address but this entry could be wholly incorrect without preventing you from sending and receiving emails.  If it is incorrect it just prevents others from replying to your emails.
If you say what email program you are using we can tell you how to find the setting you need to correct. 

[#3]

I suspect you're using Webmail and the email address of the default identity isn't correctly configured. Next time you're logged in, click Settings > Identities > Settings and make sure your email address is entered correctly there.