TyShkan,

I had exactly the same problem.

Go to your utilities folder and open keychain access. You should see your pop and smtp addresses in the list. Double click on each, go to the Access Control tab and check 'Allow all applications to access this item'.

Mail should work correctly now!

---

 Mac OS X 10.6.4 Retail || Intel Core2 Duo E8200 2.66GHz || Gigabyte G31M-ES2L || GeForce 6600 GT 128MB || Realtek ALC883 Audio || Realtek RTL8169 LAN || Samsung SpinPoint F1 1TB HD || Sony Dual Layer IDE DVD RW DW-D22A || Apple Aluminium Keyboard || Mighty Mouse

 MacBook Pro || 2.4Ghz Core 2 Duo || 200Gb HD || 2Gb Ram || NVIDIA GeForce 8600M GT

 iPhone 4 || 16Gb