[CentOS] Centos6 & 7 : unable to print from webmail

Hello All, 

I have this problem in both Centos 6 and 7, with standard Firefox, version 31.6. 
I've tested this with Zarafa and Zimbra webmail. 

Certain mails cannot be printed. These are mails that have "untrusted" images somewhere in the body of the mail. 
As a workaround : If you forward the mail, and before you press send, you delete these images, you can print them. 
I hope I'm explaining this right. 

Note : if you ever wonder what a bunch of people complain about the most when you put them behind Linux machines, it's printing. Probably 
they all of a sudden they cannot complain any more about annoying pop-ups or viruses shutting them down completely. 

I see this Em in /var/log/messages : 

May 11 10:07:03 jvermeulen dbus[994]: [system] Rejected send message, 10 matched rules; type="method_return", sender=":1.1" (uid=70 pid=985 comm="avahi-daemon: starting up ") interface="(unset)" member="(unset)" error name="(unset)" requested_reply="0" destination=":1.92" (uid=15587 pid=4069 comm="/usr/lib64/firefox/firefox ") 
May 11 10:07:03 jvermeulen dbus[994]: [system] Rejected send message, 10 matched rules; type="method_return", sender=":1.1" (uid=70 pid=985 comm="avahi-daemon: starting up ") interface="(unset)" member="(unset)" error name="(unset)" requested_reply="0" destination=":1.92" (uid=15587 pid=4069 comm="/usr/lib64/firefox/firefox ") 

I tested this on Centos7 with Google Chrome, same issue. I have not tested this with newer Firefox versions. 

Some of my ( hopefully one day ex ) colleagues let me know this does work on Ubuntu. 

Thanks for any help on this. 

Greetings, Johan