It doesn't appear that there is a question being asked here, Andrei. Could you rephrase this post to ask a question about letter-writing practices and differences between the two countries so an answer can be found?

I think you mean that the difference between Denmark and the Ukraine is that in Denmark an email is considered an official letter,but in the Ukraine you have to send a letter with a stamp by regular mail.(also called "snail mail" because it is very slow) .