Vodafone Dongle - E Mail Sending Problem

[#1]

i have a motor caravan and when we're away from home I use a Vodafone 3g dongle and my laptop to access the internet.  I can also open my Force 9 mailbox to check my Inbox e-mails. However when I try to send my e-mails I get an 'authentication failure' message . There is a workaround to use webmail from the Plusnet/Force9 account web page - but how can I overcome my original problem ?
Thanks
Harry

[#2]

Have a look at this thread http://community.plus.net/forum/index.php/topic,73459.0.html regarding using Authenticated Smtp.
Note that the Username/Password needs to be your main Plusnet username and password.

[#3]

Thanks - I'll give it a try
Harry