Hello All,
I apologize ahead of time for the long post.
I am new to this forum and had similar problems accessing Yahoo! Mail with the pre-installed email client on my X10a 1.6 android. I tried the POP Asia thing which didn't work well for me. I also tried another method where I set up the account manually using IMAP with certain settings for the incoming and out going servers, but I couldn't access the email when WIFI was on, it only worked on 3g. I got an invalid username and password.
But to my surprise I found the answer on the Yahoo! Mail for Android site. Since At&t blocks 3rd party app installs I couldn't install the mobile email app but they gave instructions to set up IMAP. The settings they gave allowed me to get my email on 3g or WIFI. Here are their instructions. Do the manual setup.
"IMAP is another way you can get Yahoo! Mail on your phone. Using IMAP you can download messages with your mobile client, so you can access your mail even when not connected to the mobile Internet.
How to set up Yahoo! Mail with your mobile client using IMAP
On your phone, press < Home >, then open the Email application.
On the 'Your accounts' page, select Next to get started with setup.
Enter your full Yahoo! address and password, then select Next.
On the next screen, you can give the account a nickname and choose the name to display on your outgoing messages. Tap Done.
If prompted, supply the following information:
Incoming Server - imap.mail.yahoo.com
Outgoing Server - smtp.mail.yahoo.com
Incoming Port - 993 (requires SSL)
Outgoing Port - 465 (requires SSL)
Username: full email address (bill@yahoo.com)
Password: is the password you login to Yahoo! with"
Hope this helps. Not sure if it works in other countries but it worked in the USA.