Related על קידושין 4:3

Converts, freedmen, mamzerim (bastards), netinim (descendants of temple slaves), shetukim (orphan with no father), asufim (orphan with neither known parent; see Mishnah Kiddushin 4:1), and any [class of people] that are forbidden from marrying into the congregation are permitted to marry each other—words of Rabbi Meir. Rabbi Yehudah says: There are 4 congregations [that are all permitted to marry each other]—kohanim, levi'im, yisrael, converts, and anyone else [not in any of those 4 congregations] is allowed to marry each other. But Hakhamim say: There are 3 congregations—kohanim, levi'im, yisrael. Rabbi Eliezer says: Anyone who is forbidden to marry into the congregation—two people who each have certain status are permitted [to marry each other]; one person with certain status with one person with doubtful status, doubtful with certain and doubtful with doubtful are forbidden [to marry each other].