But if you are using a Vodaphone dongle then your smtp settings should be for Vodaphone. It is probably smtp.vodaphone.net or send.vodaphone.net. You should ask Vodaphone or it may be in the instructions with it.
At home or when not using the dongle then you need to change back to the Orange settings.
Also a silver surfer as are many on here. It was not a basic question. Getting to send e-mails whilst out and about can be tricky (especially with wifi) which is why I use webmail rather than an e-mail client when on the move. That way you don't have to worry about smtp settings. The downside to that is with pop e-mail then you do not get a copy of your sent e-mails on your pc/laptop. But with imap you do.