Email in China

[#1]

Whilst in China last week I got the '550 Relaying denied' message whilst trying to send mail through plusnet at several different hotels.
I can understand that the ISP used by some hotels maybe suspect, and plusnet may not wish emails to be sent from that location. How can I predict when this may happen ?  My colleague did not have the same problem using a btclick account. I managed to send emails using the webmail workaround but this is an untidy option.
Secondly. When this has been triggered at one location is my account locked, or more suspect, for a certain period of time ?
Is there a way of guaranteeing that I will always be able to send emails ? Do our security setting have any effect on this ?
Sorry if this has been posted before - I did do a search.

[#2]

Have you got your mail client configured so that it can send when connected to a non-Plusnet connection (authenticating using your user name and password)?

[#3]

Did you use an authenticated SMTP connection - you don't need this when connected to a PN IP but you do when not connected to PN where you will get a relay not permitted error. Your friend probably has to use an authenticated connection to BT all the time so will work from any location.
Your account is unaffected when this happens.
Use authenticated SMTP - the login/pass is your portal login/pass.

[#4]

Make sure its authenticated (as referenced above), but do not tick the box referring to secure (SSL) connections. This is something quite seperate, and will prevent your mail client from connecting, as SSL is not supported on the PN mailservers.

[#5]

I am using Outlook 2003.
I don't have the box marked 'Log on using secure password authentication (SPA)' ticked, but on the outgoing server tab I do have my 'outgoing server required authentication' ticked along with 'log on to incoming mail server before sending mail'.
Do I just need to tick the SPA box ?
The SSL box is not ticked.

[#6]

What username and password do you have in there? It should be username not username+mailbox
Otherwise your settings look correct.
Have you managed to send email from any other non-Plusnet connection (outside China)?