2019/03/17 UUCP sends mails at the userland

When UUCP tries to execute an queued execution and it fails, it informs the admin and the sender of the task. This is done by sending mails. But when I recently tested some tasks that SHOULD fail I noticed that no mails arrived, when the job failed at my server, but they arrived when the job failed on my desktop. It took me quite a while to find out.

tl;dr: This happens because my setup of UUCP is rather special and UUCP makes some assumptions about it’s environment.

My first step, was to search the documentation of UUCP for any hints where it sends those mails to. But the only informations I found in the documentation was that it sends mails… The next step was to look into the sources of it. The execution of a task is performed by a tool called uuxqt, so I looked into uuxqt.c, and in the function isave_files we find

sysdep_mail (OWNER,
	     "UUCP execution files saved after failure",
	     i, pz);

And OWNER is usually only uucp, so it sends its Mails to uucp in the default domain. But OWNER should also be the user under which uucp runs. So I decided not to change OWNER but run the following before compiling uucp.

sed -i.org 's/\(fsysdep_mail (\)\(OWNER\)/\1"uucp@lkamp.de"/' uuxqt.c
sed -i.org 's/\(fsysdep_mail (\)\(OWNER\)/\1"uucp@lkamp.de"/' rec.c
sed -i.org 's/\(fsysdep_mail (\)\(OWNER\)/\1"uucp@lkamp.de"/' uustat.c

With this small patch in place, uucp on uberspace now works again as intended.