I can receive email but cannot send email from outlook express. pop server is smtp.mail.yahoo.com. Corect?

the full runtime error message is:
programme c:\programfiles\internet explorer\IXPLORE.EXE
i am not very computer literate so need step by step answer cant open a simple excel s/sheet

hi there. i have created an email address for my husband. problem is -he cannot receive any messages on his address. though he can send.
when tryng to send him messages, i get back a “failure …

I have alway gotten her emails,suddenly they are not coming through to me.