From: Rabbi Mordechai Leib Winkler
To: Rabbi Avraham Yehuda Leib Spreyer
The responsum addresses a question about the prohibition of deriving benefit from a Sukkah, specifically regarding smelling a myrtle branch, and clarifies that there is no prohibition of benefit in a Sukkah unless it involves nullifying a mitzvah.
Source: Yoreh Deah I §165