SendMail sending mail failed on Linux system

The problem is: After the installation of SendMail, start the service, send the message the first time to send a successful, after again no matter how to send No, change mailbox also not. After confirming that my message is sent in a format that is correct, think about viewing the mail send log:

[Email protected] ~]# Tail-20/var/log/maillog
OCT 6 23:26:40 backup-11 sendmail[1307]: T96fqeu7001305:to=<[email protected]>, Ctladdr=<[email protected] > (500/500), delay=00:00:00, xdelay=00:00:00, MAILER=ESMTP, pri=120620, relay=163mx03.mxmail.netease.com. [220.181.14.158], dsn=5.0.0, Stat=service unavailable
OCT 6 23:26:40 backup-11 sendmail[1307]: T96FQeu7001305:t96FQeu7001307:DSN:Service unavailable
OCT 6 23:26:40 backup-11 sendmail[1307]: T96fqeu7001307:to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, Mailer=local, pri=31818, dsn=2.0.0, stat=sent
OCT 6 23:26:41 backup-11 sendmail[1291]: Unable to qualify my own domain name (backup-11) – Using short name
OCT 6 23:26:41 backup-11 sendmail[1311]: T96fqf6u001309:to=<[email protected]>, Ctladdr=<[email protected] > (500/500), delay=00:00:00, xdelay=00:00:00, MAILER=ESMTP, pri=120620, relay=163mx02.mxmail.netease.com. [220.181.14.147], dsn=5.0.0, Stat=service unavailable
OCT 6 23:26:41 backup-11 sendmail[1311]: T96FQf6u001309:t96FQf6u001311:DSN:Service unavailable
OCT 6 23:26:41 backup-11 sendmail[1311]: T96fqf6u001311:to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, Mailer=local, pri=31818, dsn=2.0.0, stat=sent
OCT 6 23:30:01 backup-11 sendmail[1346]: My unqualified host name (backup-11) unknown; Sleeping for retry
OCT 6 23:30:55 backup-11 sendmail[1368]: My unqualified host name (backup-11) unknown; Sleeping for retry
OCT 6 23:31:55 backup-11 sm-msp-queue[1377]: My unqualified host name (backup-11) unknown; Sleeping for retry
OCT 6 23:31:58 backup-11 sendmail[1372]: T96dlphc039178:to=<[email protected]>, Ctladdr=<[email protected] > (500/500), delay=01:44:06, xdelay=00:00:03, MAILER=ESMTP, pri=480616, relay=mta-189.21cn.com. [183.61.185.69], dsn=4.4.2, stat=deferred
OCT 6 23:32:55 backup-11 sm-msp-queue[1377]: Unable to qualify my own domain name (backup-11) – Using short name

by looking at the above log finally let me find clues, hehe, as follows:
Dsn:service unavailable
My unqualified host name (backup-11) unknown; Sleeping for retry
Unable to qualify my own domain name (backup-11) – Using short name
Stat=deferred
Stat=service unavailable

by finding the information, the solution is as follows:
1.[[email protected] ~]# vi/etc/mail/access
# of the format of this file. (Search for access_db in that file)
# package.
#
# If you want-AuthInfo with ' M:plain LOGIN ', make sure to H
Ave the
# Cyrus-sasl-plain Package installed.
#
# By default we are relaying from localhost ...
Connect:localhost.localdomain RELAY
Connect:localhost RELAY
connect:127.0.0.1 RELAY
connect:10.0.0.11 RELAY
connect:192.168.0.254 RELAY
2. Add the following line to the/etc/hosts.allow:

sendmail:10.0.0.11  #发送邮件服务器IP地址
3. You can temporarily modify the hostname with the hostanme command, hostname aa.com;
4.[[email protected] ~]# vi/etc/mail/sendmail.cf
find:
# SMTP daemon options
Span style= "color: #000000;" >o daemonportoptions=port=smtp,addr=127.0.0.1, Name=mta
add:
Span style= "color: #000000;" ># SMTP daemon Options
o daemonportoptions=port=smtp,addr= your IP, NAME=MTA
save!

remember: After modifying the hostname, you need to restart the SendMail service, restart the service, everything OK.

Problems with SendMail sending mail under Linux system