3 letters:
bel, cel, del, fel, gel, mal, med, meg, men, mer, met, mil, mol, nel, tel, zel, mel

4 letters:
behl, bell, cell, dell, fehl, fell, gehl, gell, guel, hehl, hell, jell, kehl, kell, lehl, mahl, mail, mair, male, mall, mare, maul, meal, mech, meck, mehr, meld, mele, meli, melo, melt, meng, menn, merl, mesh, mess, meth, mile, mill, mohl, mole, moll, moul, moyl, muhl, mull, nell, pehl, pell, sell, tell, well, yell, zell, mehl, mell

5 letters:
belle, chell, delle, helle, knell, maile, maire, malle, maule, maull, mayle, meche, meehl, mel's, mella, melli, mello, melly, meloy, menne, merle, mesch, mette, miele, mille, molle, morel, moyle, nelle, pelle, selle, shell, smell, welle, yelle, zelle

6 letters:
maille, mehler, melear, meller, melley, mellie, mellor, mellow

7 letters:
mirelle, schmehl