How many words can be spelled with the letters WERDYTRELLNAE?

627.
Here they are:
ad, adenyl, ae, aery, alder, ale, alee, alert, alerted, alerter, alertly, all, alley, ally, alt, alter, altered, alterer, an, and, ane, anele, aneled, anew, ant, ante, anted, anteed, antler, antlered, antre, any, ar, ardent, ardently, are, arete, art, artel, artery, arty, aryl, at, ate, atween, aw, awe, awed, awee, awl, awn, awned, awny, awry, ay, aye, da, dale, dally, dare, darer, darn, darnel, darner, dart, darter, dartle, date, dater, daw, dawen, dawn, dawt, day, de, deal, dealer, dealt, dean, deanery, dear, dearer, dearly, deary, dee, deer, deewan, del, delate, delay, delayer, dele, delete, dell, delly, delta, den, denary, dene, dent, dental, dentally, deny, derat, deray, dere, derry, deter, dew, dewan, dewater, dewy, dey, drat, draw, drawee, drawer, drawl, drawler, drawly, drawn, dray, drear, dreary, dree, drew, dry, dryer, dwell, dweller, dwelt, dye, dyer, dyne, ear, eared, earl, early, earn, earned, earner, eat, eaten, eater, eatery, eel, eely, eery, el, elan, eland, elate, elated, elatedly, elater, eld, elder, elderly, ell, elytra, en, enate, end, endear, ender, enter, entera, enteral, entered, enterer, entree, entry, er, era, ere, ern, erne, err, errand, errant, errantly, erred, et, eta, eternal, eternally, eterne, etna, etwee, ewe, ewer, eye, eyed, eyelet, eyen, eyer, eyewater, eyne, eyra, eyre, la, lad, lade, laden, lader, ladle, ladler, lady, land, lander, landler, lane, lanely, lar, lard, larder, lardy, lat, late, lated, lateen, lateener, lately, laten, latened, later, law, lawed, lawn, lawny, lawyer, lay, layed, layer, layered, lea, lead, leaden, leadenly, leader, leady, leal, lealty, lean, leaned, leaner, leanly, leant, lear, learn, learned, learner, learnt, leary, led, lee, leer, leered, leery, leet, leeward, leeway, lend, lender, lent, let, lewd, lewder, lewdly, ley, lyard, lyart, lye, lyrate, lyrated, lyre, na, nae, naled, nard, nary, nay, near, neared, nearer, nearly, neat, neater, neatly, nee, need, needer, needle, needler, needy, net, new, newel, newer, newly, newt, rad, rale, rally, rallye, ran, rand, randy, ranee, rant, ranted, ranter, rare, rarely, rat, rate, rated, ratel, rater, raw, rawer, rawly, ray, rayed, re, read, reader, ready, real, realer, really, realter, realtered, realty, rear, reared, red, redan, redate, rede, redear, redeny, redeye, redly, redraw, redrawn, redrew, redry, redware, redye, ree, reearn, reearned, reed, reedy, reel, reeled, reeler, reenter, reentry, relate, related, relater, relay, relayed, relearn, relearned, relearnt, relend, relent, relented, relet, rely, renal, rend, render, renew, renewal, renewed, renewer, rent, rental, rente, rented, renter, reran, reread, ret, retard, rete, retell, retene, retral, retrally, retread, retry, rewan, reward, rewed, reweld, reynard, rya, rye, rynd, ta, tad, tae, tael, tale, taler, tall, taller, tally, tan, tar, tardy, tare, tared, tarn, tarre, tarred, tarry, tarweed, taw, tawdry, tawed, tawer, tawney, tawny, tea, teal, tear, teared, tearer, teary, ted, tee, teed, teen, teener, teeny, tela, telae, tele, teleran, tell, teller, telly, ten, tend, tender, tenderer, tenderly, tern, ternary, terne, terra, terrae, terrane, terreen, terrella, terrene, terry, tew, tewed, trad, trade, trader, trawl, trawled, trawler, trawley, tray, tread, treader, treadle, treadler, tree, treed, trend, trendy, trey, try, twa, twae, tweed, tweedle, tweedy, tween, twyer, tye, tyee, tyne, tyned, tyre, tyred, wad, wade, wader, wady, wae, wale, waled, waler, wall, walled, wallet, walleye, walleyed, wally, waly, wan, wand, wander, wanderer, wandle, wane, waned, waner, waney, wanly, want, wanted, wanter, wany, war, ward, warden, wardenry, warder, ware, wared, warer, warn, warned, warner, warred, warren, wart, warted, warty, wary, wat, water, watered, waterer, watery, way, we, weal, weald, wean, weaned, weaner, wear, wearer, weary, wed, wedel, wedeln, wee, weed, weeder, weedy, weel, ween, weened, weeny, weer, weet, weeted, weld, welder, well, welled, welt, welted, welter, weltered, wen, wend, went, were, wert, wet, wetland, wetly, wren, wry, wryer, wye, wyle, wyled, wynd, wyte, wyted, ya, yald, yar, yard, yare, yarer, yarn, yarned, yaw, yawed, yawl, yawled, yawn, yawned, yawner, ye, yea, yean, yeaned, year, yearn, yearned, yearner, yeld, yell, yelled, yeller, yen, yenta, yet, yew.