When it comes time to let your competing suppliers of a contract award, here is one request:
Call them. If you can't call them, send a polite e-mail. But, above all, don't just not contact them at all and make them hear about the "loss" from a third party. That's like hearing about a break up from someone other than the person breaking up with you.
Be polite. It's the only thing to do.
And, besides, if things don't go well, you might need to have a fall back plan with the rejected vendor.