Any of your contact1 and contact 2 fields can be inserted into e-mail templates.
The lookup.ini provides the ability to create a unique number in a field. I'm pretty sure there's an item on how to do this in the Heat online support knowledgebase. Regardless, it's a bit primitive and a better method might be do-able via your MSSQL database back-end and some SQL triggers.
I'm not sure, however, if that entirely answers your question as I'm a bit hazy on exactly what you're trying to accomplish.
1) Create UACCOUNTNO field in GoldMine
2) Add following to LookUp.INI:
3) Send contact an email with a link to a Web Import form that includes the UACCOUNTNO field in the URL (last parameter) eg:
4) Format your Web Import email to match on UACCOUNTNO.
So the email from step 3) includes all of the fields you would like to verify and the Web Import email sends the updated details back to you to be imported, while matching on the UACCOUNTNO field (which has to be URI encoded as the ACCOUNTNO field can contain invalid characters for a URL) as per step 4).
Thank you for your response, Doug.
I have found that the initial question (based on the information I was given initially) is not correct and that this actually involves connecting databases from external applications and importing them into GoldMine company records.
Well, this is something that would require some customization, but it's entire doable. I've done similar integration projects for many clients over the years. Feel free to contact me directly if you'd like to discuss it further.