safari Version 5.0.6 (5533.22.3) yahoo mail will not support this version . Yet I cannot upgrade to a different version ? What can I do ?

Upgrade OS X which will include a new version of Safari with it.

Alternatively, assuming that you're running 10.6.8, DL and install Safari 5.1.10 (6534.59.10).

27" i7 iMac (Mid 2011) refurb, OS X Yo (10.10.2), Mavs, ML & SL, G4 450 MP w/10.5 & 9.2.2

Try another browser as a test.

Firefox

The same happened to me, but the below answer is a temporary fix and it worked for me:

Answer courtesy of "Mike" on Yahoo Answers:

I have same version of OSX and Safari and had same problem. It appears that Yahoo mail currently has difficulty with Javascript. To get emails working again, I went to Safari\Preferences and took the check mark off "enable JavaScript". Then close Safari and restart Safari. Go to your Yahoo email and log in. You will get a message that your JavaScript is not turned on but click on the link that says to go to Yahoo mail anyway. Then email worked for me. You may have to enable Javascript for other internet websites. If you clear your cache or cookies, you will need to repeat the process of disabling Javascript. Maybe someone else has a better way of getting Yahoo email but this seemed easier than loading a new version of OSX and Safari. Hope this helped.

It can be a marked benefit to have an alternate browser. Moreover, Firefox is security updated very regularly and will almost certainly enable you to use Yahoo mail. As Eric said earlier, you can but try it. It is easily removed if you don't like it.

Incidentally, using Safari, which is not in itself supported by Apple any more, you should keep the Java option (as opposed to Javascript), unchecked except in urgent need.

Firefox would not let me download. It said I did not meet its requirements.

What version of OS X is your Mac runnng?

I am running the latest version of FireFox on OS X 10.6.8 Snow Leopard.

I am old... 10.5.8

If your Mac is an Intel CPU model then you can purchase a OS X 10.6.3 Snow Leopard upgrade disc from Apple for$20 and then update to OS X 10.6.8.

http://store.apple.com/us/product/MC573Z/A/mac-os-x-106-snow-leopard

If your Mac is an older PowerPC style Mac, then OS X 10.5.8 is as high an OS as your Mac will go.

If your Mac is a much older PowerPC Mac, you could try TenFourFox which is more up to date web browser, based on Mozilla Firefox, for older PowerPC Macs run OS X 10.4 Tiger or OS X 10.5 Leopard.

http://www.floodgap.com/software/tenfourfox/

If your Mac can be upgraded to Snow Leopard, then

Backup your important data and/or your entire Mac OS system before doing a major systems upgrade.

You can also try http://sourceforge.net/projects/leopard-webkit