I am always using my mail by visiting mail.yahoo.com.uk or mail.yahoo com through Google but logging in as and when requested to do so. I'm not using a mail programme.
I can now access my mail rapidly but the problem of not being able to send mail remains.
I can't send mail from(any of)my account(s).
As far as I know, it's the Google Chrome web browser which I'm using to access my mail. Suffice to say, I have two equivalent modes of entry, which can be on the screen simultaneously, using my usual browser with OSX 10.4.11/Tiger as computer OS
I have no further comment or questions.