Jamieson, Fausset and Brown on Galatians 1:9

9. said before--when we were visiting you (so "before" means, 2Co 13:2). Compare Ga 5:2, 3, 21. Translate, "If any man preacheth unto you any gospel BESIDE that which," &c. Observe the indicative, not the subjunctive or conditional mood, is used, "preacheth," literally, "furnisheth you with any gospel." The fact is assumed, not merely supposed as a contingency, as in Ga 1:8, "preach," or "should preach." This implies that he had already observed (namely, during his last visit) the machinations of the Judaizing teachers: but his surprise (Ga 1:6) now at the Galatians being misled by them, implies that they had not apparently been so then. As in Ga 1:8 he had said, "which we preached," so here, with an augmentation of the force, "which ye received"; acknowledging that they had truly accepted it.

accursed--The opposite appears in Ga 6:16.