Postfix- Host or domain name not found - looking up wrong domain name

Question

I want to know where i can configure the following.

I want postfix to lookup the host: myexample.com, but instead it is looking up Host-Wordpress-01. Which is my digitalocean droplets name.

How/where can i change this? I did a grep on all files in postfix and there is nothing that contains "Host-Wordpress-01". So it should be somewhere else.

Beneath is an extraction of the syserror.log

Feb 13 15:25:17 Host-Wordpress-01 postfix/pickup[29410]: 3A8D6609C0: uid=0 from=<root@Host-Wordpress-01>
Feb 13 15:25:17 Host-Wordpress-01 postfix/cleanup[29422]: 3A8D6609C0: message-id=<20150213202517.3A8D6609C0@moederpupegaele.be>
Feb 13 15:25:17 Host-Wordpress-01 postfix/qmgr[29411]: 3A8D6609C0: from=<root@Host-Wordpress-01>, size=356, nrcpt=1 (queue active)
Feb 13 15:25:17 Host-Wordpress-01 postfix/smtp[29424]: 3A8D6609C0: to=<root@Host-Wordpress-01>, relay=none, delay=0.03, delays=0.02/0.01/0.01/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=Host-Wordpress-01 type=A: Host not found)
Feb 13 15:25:17 Host-Wordpress-01 postfix/cleanup[29422]: 4247F61E26: message-id=<20150213202517.4247F61E26@moederpupegaele.be>
Feb 13 15:25:17 Host-Wordpress-01 postfix/qmgr[29411]: 4247F61E26: from=<>, size=2279, nrcpt=1 (queue active)
Feb 13 15:25:17 Host-Wordpress-01 postfix/bounce[29425]: 3A8D6609C0: sender non-delivery notification: 4247F61E26
Feb 13 15:25:17 Host-Wordpress-01 postfix/qmgr[29411]: 3A8D6609C0: removed
Feb 13 15:25:17 Host-Wordpress-01 postfix/smtp[29424]: 4247F61E26: to=<root@Host-Wordpress-01>, relay=none, delay=0.01, delays=0/0/0.01/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=Host-Wordpress-01 type=A: Host not found)
Feb 13 15:25:17 Host-Wordpress-01 postfix/qmgr[29411]: 4247F61E26: removed

I have

• setup 3 MX records for example.com referring to mail.myexample.com (priority 10,20,30)
• setup a A record for mail.myexample.com referring to the correct ip
• checked them using dig mx myexample.com and dig a mail.myexample.com
• changed the inet_protocols setting from postfix, so it uses ip4 instead of ip6

Answer 1

That's the effect of multiples configuration in postfix: myhostname, myorigin and append_at_myorigin.

When you send email with mail command/sendmail, the sender doesn't have domain parts. Because of parameter append_at_myorigin=yes, postfix append $myorigin parameter in sender name. By default value of myorigin equal with $myhostname. And value of myhostname was the hostname of your server.

Reference: http://www.postfix.org/postconf.5.html