By law, they have to charge sales tax for orders from any state in which they have a PHYSICAL presence (offices, warehouses, etc).
They've been around for at least 20 years, so yes they are safe. I haven't ordered anything from them in a long time so things may have changed but as far as I know, they are similar to most other reputable online Mac dealers.
Note that MacMall now owns ClubMac and a couple of other well-known Mac catalog resellers.
I highly recommend that if you purchase anything via mailorder or online, that you use a credit card with a good consumer protection feature, so if there are any problems they will go to bat for you.
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Randy B. Singer
Co-author of The Macintosh Bible (4th, 5th, and 6th editions)
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