There is lots of ticket software out there but it's all either PHP or ASP.Net. My plan is to to use this new solution on our main site to get SEO advantages and that site has always been Classic ASP. Anyway, that part is my problem and all I need is spare time. As admin I will be able to publish select support responses live for everyone to see. But until then support requests can be private.
For return mail addresses, unless the mail server is configured to allow specific email addresses new randomly assigned email addresses will be bounced. So my thought there was to use a new domain name similar but not the same (like support-mySite.com) and then set it to accept all emails @ that domain. This way I don't have to integrate with the mail server which is on Apache anyway. If I find a suitable Windows mail server I can do more, otherwise this may suffice.
RE: contact info "[ID#42517]" I like that idea because the spam filter can whitelist emails with that in the subject line. Otherwise responses can be sorted by email address.
Users will still add your support emails to their address book. Some may be doing that automatically. So if no ID they will get spam filtered.
My main aim is to put an end to spammers. I have clients who have purchased from us and now spamming with all sorts of rubbish. They are probably still using our web services and it will good to know exactly who.