"from" in the email bloc

I come to talk about a problem I get with the email bloc. This last notices that the email has been sent when apparently not.
Then I thought the problem is coming from the “from” of the bloc.
After testing it several times, using different address (twice the same, or not) in the part “from” of the email bloc, it doesn’t work.
Moreover my host doesn’t offer any email hosting.
Can you help me?