I don't use SuSE's default configuration, so in part I'm guessing here. Anyway DM is for masquerading, i.e. every mail (except for exposed users) to leave your machine is masqued to look like it came from username@elec.canterbury.ac.nz. If this is your machine name, it shouldn't be neccessary though.
I am guessing that elec.canterbury.ac.nz is your machine?
No way! Somehow I think I stuffed it up. When I have the machine at university, its name is xxx.elec.canterbury.ac.nz. I don't need it for email there. When I take it home, I didn't change its name. With xxx.elec.canterbury.ac.nz, a lot of hosts won't accept email from me as the name does not resolve outside uni. This is one reason I set the FROM_HEADER to elec.canterbury.ac.nz - it's incorrect, but it resolves. But then I can't send email to university :-(. Perhaps the better question to ask is: what host name does one set for dial-up networking? Where? Is it ok to change the host name in ip-up.local? Does a masquerading host always relay? Perhaps I'm thick, but SuSE asks the question as "What From header to put into mail and news postings", which is inconspicious enough, but when that leads to open relays I have to ask myself whether that is a bug in SuSE's setup. Volker