Mac OS X v10.6: Mail.app won’t open, or "You can't use this version of Mail…" alert after installing Security Update 2012-004:
Fellow user Grant Bennet-Alder offers this solution:
Some users have reported this problem if the Mail Application has been moved out of the top-level /Applications folder, or duplicated in another location.
When the Security Update is done, the old version of Mail is disabled.
The solution has been to:
1) make certain Mail is in the /Applications folder
2) There is no other copy anywhere else.
3) Once steps 1 and 2 have been done, Manually download and re-apply the Security Update (2012-004) by hand.
If the Mail.app has been LOST, it can be re-installed by applying the 10.6.8 version 1.1 combo update. But this update is quite large and it is usually not necessary:
I get msg that says "mail cannot connect to yahoo please input Password". same email i used before installing newest mac os system.
The newest OS is Mountain Lion. Therefore, that is forum you should be posting in instead of Snow Leopard. Also, correct your system information in your profile to reflect your new OS.