Mail command cannot send mail

Mail command cannot send mail-Linux Enterprise Application-Linux server application information. The following is a detailed description. Cohoohoxiong

Occasionally, I find that the mail command on my machine cannot be sent, and I read the error log:

Jul 4 15:08:20 cocobear sendmail [4167]: m6478JxK004167: to = cocobear.cn@gmail.com, ctladdr = cocobear (500/500), delay = 00:00:01, xdelay = 00:00:00, mailer = relay, pri = 30113, relay = [127.0.0.1] [127.0.0.1], dsn = 4.0.0, stat = Deferred: Connection refused by [127.0.0.1]
The mail status is Connection refused by [127.0.0.1].

It turns out that sendmail has a problem with the default configuration in Fedora. After modifying the corresponding configuration file according to the above article, restart the service and then use mail to send the mail.