When you send Emails to the NVC how long before confirmation is sent back ?

I emailed NVC once and got feedback approx. 7-9 days later.

We sent the email on 4/01/08 and immediately received the automated response. The choice was accepted about a week later. I would recommend resending email to make sure that the response show up:

PLEASE DO NOT RESPOND TO THIS AUTOMATED NOTIFICATION

Thank you for your recent inquiry to the National Visa Center. This
automated email is to notify you that we have received your inquiry. We
prioritize our emails in the order in which it was received, and will
respond to your inquiry as soon as possible.

In my case it took NVC 7 days to answer. This includes the weekend,
so actually 5 working days was my wait.

Just as an FYI...

I mailed my Choice of Agent form on Monday, it was received at NVC on Tuesday and was in the system on Friday. But they didn't update the automated system until the next Monday (I called on Friday and got this info from the operator).

Just an option for those who still want to mail the form in.

Although it may not always be the case, it seems like e-mailing takes a bit longer.