The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in Parashat Balak (5), discusses the Halachic status of brandy produced by non-Jews (listen to audio recording for precise citation). Brandy begins as wine, and is then processed into a liquor. The Ben Ish Hai writes that despite the fact that the wine is transformed, it nevertheless retains its status as wine with respect to the prohibition of Setam Yenam partaking of non-Jewish wine. Therefore, one may not drink brandy produced by non-Jews. Brandy is permissible only if it bears reliable kosher certification.
However, the Ben Ish Hai adds, the prohibition of Setam Yenam does not apply to wine that is mixed with other ingredients such as honey, pepper or other spices that change its flavor. Even though the product is still referred to as "wine," nevertheless, since its taste is fundamentally altered by the honey or spices, it is not considered wine. One may therefore partake of such a drink even though it was handled by a gentile. However, if only a small amount of spices was added, such that the wines taste is essentially the taste of wine, then it is still considered wine and it thus becomes forbidden if it is handled by a gentile.
Summary: Brandy produced by gentiles is forbidden, and brandy therefore requires proper kosher certification. Wine that contains other ingredients such as honey or spices that fundamentally change its taste is not considered wine, and it therefore does not become forbidden if it is handled by a non-Jew.
