pop3 email can't send when away from home

[#1]

Using windows 7 and windows live mail my plusnet email works fine at home but when I take my laptop away I can only receive emails not send them.  Any ideas what I am doing wrong?
(hotmail and gmail accounts work fine).

[#2]

Yes, you need to setup your outgoing(smtp) server to use authentication. See here http://www.plus.net/support/email/setup/windows_live_mail_smtp.shtml

[#3]

It's more complicated than that.  A lot of ISPs will block traffic on Port 25 unless it is directed via their own outgoing email (SMTP) server.  But AFAIK Plusnet do not provide an alternative to using Port 25.  This means that when you are connected to the internet via another ISP (not Plusnet) you often simply won't be able to send emails via Windows Live Mail.  In which case you will have to logon to web mail on the Plusnet web site and use that; exactly in the manner you use Hotmail and Gmail. 

[#4]

Plusnet have enabled port 587 for sending if port 25 is blocked. Still needs authentication if not on a Plusnet connection.

[#5]

The alternative is port 587 http://community.plus.net/forum/index.php/topic,105310.0.html

[#6]

You will need to go to the Advanced tab to change the port setting (sorry I had not known that was an option).