I was having this same issue but with AT&T in the US, who also uses Yahoo's email system.
Here's what worked for me. I can't account for why exactly it worked, but it *immediately* eliminated the error message I had been receiving up to that point.
I simply logged in to my AT&T webmail and upgraded to the "new mail" service from the "classic" version. And that was it!
The next time I opened my mail client (Windows Live Mail), it was like a log jam had cleared up. Messages started pouring in, including ones I had already received. I temporarily cancelled the download and went back to the webmail to delete all the old messages that had amassed there (14k+!). Since then, I've had no problems sending or receiving emails through my email client.
Hope that helps at least one other person out there!
Had a call from BT yesterday wanting to take some more Wireshark logs to compare what Yahoo Mail was doing differentlly to GMail (Which works perfectly using POP3 & SSL). However after several attempts we were unable to get even a 15Mb attachment to fail. I do not currently have SSL selected on my Yahoo mail either!
Strangely enough the day before I had an email arrive in my inbox that was old!!!. It would seem that the problem has gone away. I am assuming that BT or Yahoo have implemented some sort of fix. I have asked what they have done and am waiting for a follow up call. If I find out I will let you all know. That said I have everything crossed that this situation will last.
If it is fixed 1 am going to miss my weekly chat with the Support Desk whom I have found nothing other than willing to try and sort this out. Not sure that the same applies to Yahoo though. It would appear that I am going to miss out on a birthday card (The fault would have been 12 months old in March).
Watch this space....................
Hi Liquorice - I imagine whatever they did to my mail account they need to do to yours. I have emailed BT asking for an explanation of the fix. Will post result when known.
What a rollercoaster ride I am getting with BT. Elation one minute and despair the next. Two days without problems despite my very best efforts to break it!!! Loads of emails with large attachments (up to 16Mb) sent and received without problem. Told BT (and all of you) I was fixed. Today even emails with no attachment are occasionally failing. Have escalated back to BT again (Grrrrr). What I really am having difficulty understanding is the inconsistency of it all. Throughout all of this my Gmal working perfectly.
SO I am truly sorry for raising false hopes - really thought they had cracked it !!!
Don't worry about giving us the false hopes, quite understand your frustration. As has been said before probably the only solution is for BT to ditch Yahoo! Good luck