[ingo] blacklist problem

[Nico Faerber]

hello list

we have a lot of user who accindentally add important addresses to  
their blacklist and don't realize that.
(for example by pressing ctrl c on their mac,...).
i would like to add a check so that addresses which match on a certain  
regex can't be added to the blacklist and instead a message pops up to  
inform the user.

any hint where i have to hack the code to achieve this?

thanks in advance

Nico