* BYE on an error is the server saying "I can't work with one of your messages so I'm not going to let you work with any of them". I don't find that a helpful approach to the end user. The client will probably just reconnect and attempt to FETCH the problem note again, get * BYE again and so on ad nauseam.
All of which should indicate that the server is broken, that it's time to call a wizard to fix the server, and that paws should be kept off until the wizard has fixed it.
A tagged NO lets the user get on with the rest of their mail ...
In this case, that "get on with the rest of their mail" can result in loss of data. That is not a way to win friends with customers.
The underlying thing which you are missing is that you should *not* be thinking about all the good ways to recover from "horrible error 69", but rather you should be thinking about all the good ways to prevent "horrible error 69" from happening in the first place.
If your mail store is vulnerable to having pieces of it be unexpectedly inaccessible, you should be fixing those vulnerabilities.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
