I've heard here that it's a normal function of the intestinal lining, but I really don't feel that way. I see far too much of it myself for it to me normal. My colonic lady said your body is building up all that mucous in defense of an invading organism ( in our case, candida ). You should have seen the colonic tube when I went through about 6 months of colonics a few years back- wow- absolutely tons of that yellowish mucous!!
I don't see nearly as much as I used to though, so I think my body is healing, albeit, very slowly :-).