I do not think I understood the meaning of all three zones.

There are 2 basic zones. The red one is for spam, while the green one is for friends. However, sometimes you cannot correctly identify quality of a received letter before you receive it.  The yellow zone is designed for such letters. The letters from this zone are not added to any filters, and you receive all these letters, and then decide what to do with one or another letter. Furthermore, if the program is unable to classify a letter as one from a friendly user or from a spammer, such letter will remain in the yellow zone, waiting for your correction.

SpammersÆ addresses constantly change, and that is why I do not feel like including them to the Black List.

It is enough to drag the letter you need to the necessary zone, and the program will automatically add essential changes to the corresponding filter.

Is it possible to infect my computer by receiving a letter using your program?

It is impossible, since the program receives nothing but the titles of the messages.

Can your program delete manifest spam right away automatically?

For this purpose, the Fiery List of Rules is designed. All letters, which meet the requirements of this list, will be deleted during synchronization, and you would not see them in the lists. The program does not add new rules to this list automatically. Please be careful when adding new rules.