i don't know about being judgemental on this......we've all done this in one form or another.
i tend to do it more verbally than in emails, which can be just as bad or worse.
there's something very powerful about email communication...it's both very liberating and intimate, yet still has the responsibilities of a published letter of sorts, since once it's out there, it's semi permanent.
i think in the long run, the recipient of any email understands that it is just a slice of (your) life at that particular moment...and we all have episodes that are better or worse than others, so no harm done.
you can always send a retraction/explanation that you weren't thinking clearly at the time.
end of problem.