host map: lookup ( ): deferred
It is the log info in mailq.
NOQUEUE: SYSERR(root): opendaemonsocket: daemon MTA: server SMTP socket wedged: exiting
It is the log at /etc/log/maillog
I use sendmail to send mail. I can use 'mail' to mail to local users, but I cannot mail to others. For example, I sent a mail to email@example.com, which could not run. A mail to root can be sent and received.