Am 04.07.2017 um 19:13 schrieb Gordon Messmer: > On 07/04/2017 09:21 AM, Chris Olson wrote: >> It remains a mystery what could have happened during a standard yum >> update of the system to cause this domain and/or host related sendmail >> issue. > > > Run "hostname". Has the hostname changed? Run "ls -l /etc/hosts > /etc/resolv.conf". Have those files changed recently? > > It's possible that this system was working in the past because its > hostname was set up in DNS, and was removed. In that case, the problem > wasn't related to "yum." sendmail would (IIRC) continue working after > the system's hostname was removed from DNS, until the next time the > system rebooted. Sendmail demands a hostname with at least a single dot in it. "computer" is in no way a valid FQDN. "computer.localdomain" would be fine and if it has an entry in /etc/hosts. Alexander