Acknowledgement of receipt on emails ??....

do you know if its possible to send emails thrue safari or whatever and having a proof that recipient has received or read the email like an acknowledgement of receipt ??


No... I don't think it's possible with web based mail.
OutlookExpress is a Microsoft product. You can't use it on a Mac unless you have a Windows partition installed.
I think AOL is one of the few email clients where you can be notified when when a recipient email has been opened.
You need to check with Firefox support to see if they support email acknowledgement notifications.