exchange 2010 FQDN problem in Message-id

Something happened to my exchange 2010-server, and we're getting "sender IP must resolve" -errors from all over.

The problem is, that I have FQDN set as mail.mydomain.com, but nevertheless in message it shows as servername.mydomain.local (you can see from attached picture and the message header below)

Whatever I put there, it simply keeps pushing out the .local in message-id, and we keep being blocked in antispam.

How do I change that? I'm pretty positive that the root cause for the error message is this .local thing.

Our MX-records for the domain:

mx 1 mail.mydomain.com
mx 10 mail.backupdomain.com
TXT       mydomain.com.       v=spf1 a mx


And here's the message header


Received: from myserver.mydomain.local ([fe80::a9ff:d115:132c:5db3]) by
 myserver.mydomain.local ([fe80::a9ff:d115:132c:5db3%28]) with mapi id
 14.03.0123.003; Wed, 7 Sep 2016 00:52:42 +0300
From: "Me" <address>
To: "TestDude" <address>
Subject: test
Thread-Topic: test
Thread-Index: AdIIiPoMQiQ24arUSU2tIVQ6ZGSnZQ==
Date: Tue, 6 Sep 2016 21:52:41 +0000
Message-ID: <3766E2CABFB74944ACC400AC41D1AAACAF6442E2@myserver2.mydomain.local>
Accept-Language: fi-FI, en-US
Content-Language: fi-FI
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [92.159.55.22]
Content-Type: multipart/alternative;
 boundary="_000_3766E2CABFB74944ACC400AC41D1AAACAF6442E2myserverre_"
MIME-Version: 1.0
fqdnconf.png