Contact
email My preferred email address is prumpf@tux.org. If that doesn't work, prumpf@ftp.uk.linux.org might. There are also a number of email addresses that shouldn't be used anymore: prumpf@jcdbs.lanobis.de, prumpf@suse.de, prumpf@puffin.external.hp.com, prumpf@mkp.net, Philipp.H.Rumpf@mathe.stud.uni-erlangen.de, prumpf@mandrakesoft.com are some of them.
phone My home phone number is +49 30 86420735; if you don't know how to read this, or you can't work out when it is okay to call me, or, in fact, you don't have a very good reason for wanting it in the first place, I'd appreciate it if you sent email instead.
classical mail My recent experience suggests that this method of communication is even less reliable than email, and probably more expensive than a phone call. Still, if you absolutely have to send something that way, the address is: Philipp Rumpf; Gartenstraße 25; 37073 Göttingen; Germany.