Question: Store Vector elements in rows as txt.

I have a vector (matrix) that looks like this. I want to save it to txt text. But the Export function doesn't seem to do that.

M:=Vector[column](10, [{{a, b}, {b, c}}, {{d, e}, {e, f}},
{{d, f}, {e, f}}, {{a, h}, {h, i}}, {{a, i}, {h, i}},
{{d, e}, {d, f}}, {{a, h}, {a, i}},{{c, d}}, {{a, b}, {a, c}}, {{a, c}, {b, c}}]);
Export(M,"E:\\M.txt");

Error, (in Export) invalid input: Export expects its 1st argument, input, to be of type string when target=file, but received Vector(10, [{{a, b}, {b, c}},{{d, e}, {e, f}},{{d, f}, {e, f}},{{a, h}, {h, i}},{{a, i}, {h, i}},{{d, e}, {d, f}},{{a, h}, {a, i}},{{c, d}},{{a, b}, {a, c}},{{a, c}, {b, c}}])
 

I found that I can save it in xsl format.

with(ExcelTools): Export(M, "E:\\M.xls");

How to save M in txt format below?