The California DMV does this as part of their “upload documents ahead of time” system, and it is a terrible experience, because they often tell you to wait for

The California DMV does this as part of their “upload documents ahead of time” system, and it is a terrible experience, because they often tell you to wait for an email and then no email arrives. What happened - is there a problem with my spam filter? Is there a backed-up queue in the DMV software? Do they simply consider it acceptable if the email takes an hour to be delivered? If you use this method then you really need to care about your email deliverability and that is harder than just maintaining a regular login process.