enabling features in packages

[Serban Udrea <S.Udrea%gsi.de@localhost>]

Hello,

I hope this is the right place to ask this. If not just let me know.

Please consider that I am very new to NetBSD.

I have the following problem: I would like to enable for some packages features which are 
not enabled by default when building them from pkgsrc. One example would be, to enable mysql 
lookups for exim. What is the right way to do this when using pkgsrc?

Any help is highly appreciated.

Best regards,

Serban Udrea

PS. I know that the best way would be to learn from the docs but I am quite 
under time pressure.