hello, in this thread a user has found out that the problem might be related to the ghostery addon - do you have it installed too?

if so, add an exception for yahoo mail: click on the ghostery icon while you're in yahoo's webmail, choose "edit blocking options" & then don't block on this domain...

It worked. Thank-you. Will check all my other yahoo e-mail accounts to confirm. Love Firefox. Hate explorer.

Same thing just started happening to me and YES I use ghostery and love it and dntm by albian.. and yes, I love my Firefox. HATE that I can now only respond and compose emails in yahoo if I let my emails be read and tracked!! Just started happening... maybe with the last "update"?! REALLY dont want to stop using yahoo but refuse to have my emails read and tracked..... any help there Mozilla? PLEASE. THANK YOU! d

p.s. Mozilla can you PLEASE remove GoogleAnalytics from your pages too since I have no problem giving YOU my info but do NOT want Google taking it and selling it to the highest bidder! BIG part of WHY I use Mozilla products and NOT Googles. Again THANK YOU! D

Another source of the problem with yahoo, amazon, and several other sites and firefox up to version 18.xx is ad blocking software. Adblock plus 2.2xx add-on plugin successively blocks the loading of content on and throughout Yahoo and other sites. The adblocking software also effects Comodo dragon, ice dragon, and Chrome Where yahoo and amazon are concerned.

Firefox in linux (ubuntu) does not have this ad blocking problem using the same adblocker.

Disable or set your adblocker to exclude yahoo, and or other sites from the content block.

So. It would appear that if you wish to continue to use yahoo as your primary email AND block them from reading and tracking you emails then you will have to configure "Thunderbird" to retrieve and send your email. It appears to work just fine and dont think anyone else will ever know the difference. Did it earlier and seems to be working great for the moment. Will update as time goes on if something shows up that is not working. Good luck all.

I encountered a simaler problem where I could not compose or reply to emails; I based on what I read here I tracked the problem down to AVG Do Not Track. When I turned it off for mail.yahoo.com it mail began working properly again.