[xom]

"valid through August 19"

[grecy]

I've always found "through" to be confusing when used like this. It's like the whole "Next Friday" thing - is that the one about to happen (it's the "next" one to occur), or is it the one after that? (in Australia, it's usually the later) I much prefer "valid until August 19"

(I'm a native English speaker, not from the US where "through" seems more common)

[metageek]

Right. "Through" is better than "until" because "until" leaves the reader unsure whether it includes August 19th. And 2011 is unnecessary; if someone does find an old message, they can look at the Date: header.

Personally, I would say "August 19th", not "19".

[reemrevnivek]

Agreed, especially with the dropped year.

If the duration is less than three months, the year can be inferred from the date of the email.