Question about Outlook Express

I found out about 2 weeks ago that my WLMail default account was not sending emails.
To try and fix it I uninstalled WLMail and reinstalled it but still the account would not send my email.

Here is an example of the error messages:

An unknown error has occurred.

Subject 'Draw data since start of lottery'
Server Error: 550
Server Response: 550 5.2.0 Mail rejete. Mail rejected. ouk_513 [513]
Server: 'smtp.orangehome.co.uk'
Windows Live Mail Error ID: 0x800CCC69
Protocol: SMTP
Port: 25
Secure(SSL): No

Yesterday I wanted to fix this as it is of course very frustrating that WLMAIL is not working properly.
First I did a check ping to the server and this gave this error:

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\Richard>ping mail smtp.orangehome.co.uk
Ping request could not find host mail. Please check the name and try again.

I then contacted my email provider and they checked my account and said there were no problems with it so it must be a WLMail problem and suggested I make a new account. I duly made a new account for my default email and amazingly, it works properly, sending and receiving!
Why has my original default account broken and why can it not be repaired?

I could now delete my original default account and try using the new account but my original account has many folders with message rules I want to preserve and it will be a pain to have to manually make new ones and move the mail over on to the new account! Is there some way I can copy the default account folders and message rules?

I am grateful for comment and help and advice and look forward to replies, thanks