Yes ... email is now unreliable and can not be trusted.
I have a system that's been running about eight years that sent status reports at various times during a work-flow. (RficSubmission.org) About four years ago many of the customers started emailing to have me manually check the status because they weren't receiving the emails.
I tracked this down and discovered several SPAM prevention measures were preventing my status messages from reaching their destination. So I started saving every status message on the system so that when the customer logged in they could check them. Part of the instructions told them that, if they weren't getting regular status updates to log in and check them on the web site. This cut down on a lot of the administration overhead.
Of course this doesn't address your problem which sounds a lot like an authentication issue. The airlines in the US handle this by letting passengers print out boarding passes from the web site and at the airport.
It also occurs to me that if you're using a printed email to authenticate something, it could be very easily forged with a text editor.
Yes ... email is now unreliable and can not be trusted.
I have a system that's been running about eight years that sent status reports at various times during a work-flow. (RficSubmission.org) About four years ago many of the customers started emailing to have me manually check the status because they weren't receiving the emails.
I tracked this down and discovered several SPAM prevention measures were preventing my status messages from reaching their destination. So I started saving every status message on the system so that when the customer logged in they could check them. Part of the instructions told them that, if they weren't getting regular status updates to log in and check them on the web site. This cut down on a lot of the administration overhead.
Of course this doesn't address your problem which sounds a lot like an authentication issue. The airlines in the US handle this by letting passengers print out boarding passes from the web site and at the airport.
It also occurs to me that if you're using a printed email to authenticate something, it could be very easily forged with a text editor.
Peace,
Rob:-]