confusion about emails not sent

[#1]

As per my previous post I am new to plusnet. I have set up email and set up address book. I have notified contacts and had most of them confirmed. I have then sent some second emails to these contacts and had messages back from mailer to say unknown address for recipient. So how was the first email sent and recd. I have then sent another email and this arrived. Typing was not at fault as these were sent via my address book/. Is this teething troubles

[#2]

Which e-mail client are you using, or webmail? 

[#3]

webmail peter I have a plusnet email address

[#4]

I see from yout other post that you have made contact with other members interested in webmail.
Have you considered using Outlook or other e-mail client?
You can still use Yahoo or Gmail