On reply dont use [Delivered-To] address as From address

Hi,

I find that the following behavior is not desirable.
if using two addresses (address-one is automatically delivered to address-two by its server), when i receive an email in address-one, it is delivered to address-two.
When replying to this message, the `determine_sender` function find both address-one and address-two to match, but if address-two is the main address it is chosen upon address-one (which is to be preferred i think).

In this pull request I comment out the `Delivered-To` address. Now the `address-one` is chosen by default.