Re: I like Costa (Email Contact addresses should be required)
@ Trigonoceps occipitalis:"OK, but please let me have the option of a copy sent to my email."
I see your point, but this can be a risky thing for a company to do...you would then run the risk of
1) Your webform being used as a spamming engine (if it's only relaying messages to your customer support address then it's fairly easy to lock down; but if you allow it to send to multiple addresses, some of which are user-defined it all becomes more tricky). Remember also that if your webform gets caught spamming, your whole domain will be locked down for at least a couple of hours until you can get yourself out of the blackhole. Possibly multiple domains, if they share the same IP address. During that lockdown, people attempting to contact you will not be able to send you email; and that can be expensive; possibly disastrous. At the very least, it doesn't look good.
2) Badly set up forms (ie, where it is not explicitly stated in the body text that this message is from a webform at $site) could also be used to send convincing messages from a genuine live company address. Pretty sure there is some potential for havoc there.
The standard response is to send a very basic "yep we got it" email out automatically. Your message is normally stripped out/not included due to data protection. It's not uncommon for people (especially to support and similar) to have personal details, identifying information, maybe passwords. There's no way in hell a company is going to risk sending that, sight unseen. That's also why support emails from a company generally don't copy the whole conversation (because -amongst other things- it would give an attacker multiple chances to get their hands on delicious personal information).
As soon as a company sends an email, they become legally liable for the contents.
So while your request seems simple -and technically it is- it's entering shark-infested waters, legally speaking. It's not that nobody has thought of it; but if you consider the public reaction to both spamming and data breaches (and your proposal has potential for misuse in both areas); can you really blame companies for not wanting to go there?