The system currently allows someone to send an estimate to a client when it's in "archived" status and the email references the client portal with a "view & approve estimate" button. However, when you click on this button, the client portal doesn't work.

This results in the client having a bad experience (sees junk that "doesn't work" as far as they can tell -- very unprofessional) and the sending wouldn't have any idea it's even happening as there is nothing preventing them from doing it nor is there any warning indicators.

The system should protect the clients from a garbage experience as a TOP PRIORITY.

The ideal fix would be to simply upgrade the client portal to allow it to work with archived estimates. Who says you might not have an customer who you thought was lost but later turned out to be active? I think this isn't uncommon.

If that fix isn't possible or isn't desired from someone else's perspective, you should prevent someone from doing it OR AT LEAST advise them that they're getting ready to do something improper. I cannot imagine any scenario where we want "junk" going out to customers!