We run a sendmail 8.14 server for a domain which has its user database managed in NIS. My nsswitch.conf is pretty vanilla:
passwd: compat group: compat shadow: compat hosts: files mdns4_minimal [NOTFOUND=return] nis dns mdns4 networks: files protocols: db files services: db files ethers: db files rpc: db files netgroup: nis
If the NIS service is for some reason down, sendmail permanently rejects emails to our users, which is really undesirable. When DNS is down, other pathologies also occur.
I'd like to have sendmail refuse to receive email if the NIS or DNS services are down. Is there a way to configure sendmail to do so?