The first thing you will have to do es this. Try a telnet test against that domain on port 25, and send a test email, if that email goes trough then you should check the "action taken" on the email that is in the outbound quarantine.
Second test, try disabling the TS and send that email, maybe that domains aren´t trusted.
let me know!,if you can go ahead we should workaround it!
Trusted Sources is one of many modules to fight back against SPAM. The AV and the SpamProfiler are the ones that block almos the 95% of the Spam. I´m nos suggesting that you disabled it for good. Only to test against that domains.
answering your question, disabling it for 10 minutes and try send email to that domain wont do any harm!
How about that logs on the Action Taken in the outbound quarantine?
let me know
If the emails are in the outbound queue of the ironmail then its already passed trusted source. What you want to do is look in logs and see whats happening to the email. First find a message id and then either go to Queue Manager -> Queue Search and search by the message id, or you can log into the cli and just do showevents | grep <msg id>.
Let me know what you find or if you have any other questions.