There is already a button on the profile page that allows anybody interested to send the profile's owner an e-mail. How much easier can it get?
Example: “XYZ Translations would like to add you to their database of service providers. If you accept, please select ACCEPT. The company is also requesting that you provide the following information: …”
Such an e-mail would cause an immediate negative reaction on my part. If somebody is really interested in a mutually beneficial collaboration, they should (and do) send you a personal e-mail.
Isn't the inital contact/answer e-mail also a good source of information regarding the seriousness and respectability of/for both outsourcer and translator? Why should the translator have to do all the legwork to find out even the most essential background information on this outsourcer? In contrast to your suggestion, I would encourage the outsourcer to provide as much information about them and any potential future work as possible.
This is BTW already a Proz requirement:
When posting a call for CVs for potential future projects, it is very important that you post complete information about your company and the types of jobs you tend to obtain. Your posting may be removed if such information is not provided.
There is enough impersonal exchange going on already (with enough people complaining about it), identical e-mails sent to who knows how many recipients. Why encourage that any further? Translators should not be treated as a commodity you can order with the click on a button!
Many times agencies request CVs, etc. from translators/interpreters not for a particular job, but for future use. This then requires us to contact them even though most of the information is already available on our profiles/websites.
If an outsourcer is reading the forums, knowledge articles or searching the translator database and sees a translator they would like to work with in the future, they can simply push a button.
Most (all?) of these requests come via the profile page anyways. If they still request a CV from you after reading your profile page, why would they not request one if they could just click on a button? Particularly if this button would encourage outsourcers to contact you not via your profile page but from any other Proz page. This would only increase the amount of such requests.
As you say yourself, they need to have the option to request additional information. What makes this e-mail then so different from their own personal initial contact e-mail - except for leaving out all the information relevant to the translator and his/her decision to work for the outsourcer?
Why would such a button make more outsourcers come to you than they already do? If so, only those that are too lazy to write personally, or those thinking: OK, why not, let's add a few more. But just being in somebody's database -- particularly added in such an unprofessional way -- won't make much difference for the bottom line IMHO.
BTW, Proz.com Connect tool for outsourcers offers -- hopefully more efficient -- features for that very purpose:
ProZ.com Connect! enables you to source and manage quality translators from the world's largest network of more than 170,000 linguists, representing more than 100 languages.