When we send out the subscription emails we receive a number of "failed to deliver" messages. These are mostly due to changes at the destination. If you believe that you are missing any messages please check your account details. We have published an FAQ which covers this topic.
We also receive a number of returned emails which have been rejected by Spam filters, if you have installed such software on your PC please check to see that you are allowing our emails through.
We monitor the number of failures we receive and if it is obvious that the failure is terminal we delete the accounts.