Hi,
I could see this static nat statements for the same internal ip for port 25 and 110.
ip nat inside source static tcp 10.6.1.2 110 interface FastEthernet1 110
ip nat inside source static tcp 10.6.1.2 25 interface FastEthernet1 25
Also i could see this line in the acl 105, which is applied on the fastethernet1.
access-list 105 permit tcp any host 10.6.1.2 eq smtp log
But i dont see any acl entry to allow the pop3 port for 10.6.1.2.
Can you check whether you have properly allowed the interesting traffic via the access-list 105.
HTH
-VJ