On a Koha fresh install Koha install and ask for setup info for nullmailer package. As this sometimes doesn't look mandatory is usually left unconfigured: bad mistake: This make mail.log increase in gigabytes steps until runing out of space (as Marco Moreno says on bug #12364/c1): $ ls -lahS /var/log/mail.* -rw-r----- 1 syslog adm 39G Dec 14 06:46 /var/log/mail.log.1 -rw-r----- 1 syslog adm 15G Dec 19 08:20 /var/log/mail.log -rw-r----- 1 syslog adm 11G Dec 14 06:46 /var/log/mail.err.1 -rw-r----- 1 syslog adm 4.0G Dec 19 08:20 /var/log/mail.err .err white lines like: nullmailer[938]: Sending failed: Host not found
I believe this sounds more like a system administration than a Koha issue. Please reopen if you disagree.