Cannot sent EMail through Microsoft Outlook Account
I have Microsoft Outlook 2010. I have added Yahoo Mail Account (Premium because the ordinary one does not offer POP) to it through POP. I managed to receive all the mails from the Yahoo Mail Server to the Microsoft Outlook Account some time backabout a year ago. I also managed to sent EMails through Microsoft Outlook using the Yahoo Web Mail POP account to Hotmail accounts and other accounts successfully. However recently I tried to sent an Email through Microsoft Outlook using the POP Yahoo Mail account but the message goes into Outbox and remains there in spite of repeatedly pressing send and the using the send and receive button all at the top left hand. The other two accounts on the Microsoft Outlook are anchronistic dial-up ISP accounts which I hardly use. Who uses a dial-up modem to send emails these days?
Will somebody tell me what is wrong and how will I be able to send the Email through Microsoft Outlook using the POP Yahoo Mail. Yahoo Mail Server does have not a word processor like Microsoft Outlook does.