I have been using firstname.lastname@example.org as main email for years without facing serious problems. Including changing my operation system from Windows into Mac, from mail apps Outlook into Entourage (Outlook on Mac) or Apple Mail. Everything did beautifully until few days ago.
I realized that Yahoo.com the main server in US changed their policy about forwarding email using POP and IMAP last year. They're not allow new account to using this facilty anymore. Most of regional Yahoo though still allow to do this as I enjoyed yahoo.co.uk for quite sometimes ago. I reckoned they did it because change their email system into Outlook-ish than the Classic type.
I received number of confirmation about changing my password through Apple Mail. Yes indeed I always change the password every 2-3 month but the messages became more persistent. I thought my computer had silly mistakes or Leopard crashed my cookies again. I checked and just notice that yahoo.co.uk change their server port for both upcoming and outcoming messenges. God sake! why they've did it without notify their customer?
On their Yahoo Mail (hidden on setting your POP and Forward) as :
Pardon our appearance during construction. We're still tweaking the Yahoo! Mail POP & Forwarding option. Temporarily you'll need to access it through the Yahoo! Mail Classic interface. But, rest assured, any changes made will take effect once you've reloaded the Yahoo! Mail.
I have been looking around to answer those problem. Some of them quite useful as in Apple Support site. But since this disruptions come to light there is NO official (or logical) explanation about this. Some of people suspected that Yahoo try to increase usage of Yahoo Mail Plus which will cost $19.99 a year exactly what they did on Yahoo.com.
Finally I came to end of it by saying goodbye to Yahoo UK. The reasons are because I am not willing spend that amount of money for free email, and also I'll get another services from Google which give me 2GB storage room. What I need is an access to let me download my email into system that recognized nicely both in Apple and Windows.
Gosh! I have to reconsolidates all the account that use this email. It might hundreds of them. I am really pissed off with Yahoo UK.
Please contact me in future with : email@example.com or firstname.lastname@example.org