[screensaver400]

I'm trying to select typefaces for an email newsletter template. We've designed it with Helvetica, but obviously few Windows PCs have the font, so Arial would be the second choice. However, Helvetica looks awful on Windows, for the few people that do have it.

Could I just put "sans-serif" as the only choice? I'd hope that it would default to Helvetica on Mac, Arial on Windows, and whatever Helvetica clone is available on Linux on that OS.

Are there any problems with this?

[chucker]

font-family is designed to let you put them in decreasing order of specificity, so in your case, just write:

font-family: Helvetica, Arial, sans-serif;

If Helvetica is available, that will be used. Otherwise, if Arial is, that will. Failing that, any preferred sans-serif typeface will be used.

[screensaver400]

Yes, but I'd prefer Helvetica to never be used on Windows.

If I put Helvetica first, some Windows machines will display it. If I put Arial first, then Helvetica will almost never be used on Mac.

[chucker]

Ah, now I understand.

You can't really rely on sans-serif defaulting to Helvetica on the Mac than you can on Helvetica being ugly in Windows (it's gonna look somewhat better in IE 9).

If you really want to ensure that it looks as you intended, supply the typeface yourself using @font-face.