I'd start to be concerned over 50ms.
Pay for the what now ? I can logon to my bank online, and given any sort code and account number transfer any sum of money I choose, (that I have available), for free. This is standard across any UK bank I am aware of. Lots of these types of transactions are instant now too, (or certainly very quick), some institutions still drag and you have to wait a day or so, but they are becoming fewer.
A lot of banks also have a great deal of large companies details stored for you, making it equally as easy to pay any bill.
now we could feed THAT into a flux capacitor.....
The only requirement is to keep the logs for a year, from/to/time/date. Their thoughts (rightly or wrongly) is they want to be able to bring email inline with telephone records, where they can find out who called who and when - but not what you spoke about (we'll leave that to Echelon).
I've noticed several design suggestions in your code.