postfix not sending email out, but is receiving

[NepZeb]

Hi guys, I am just breaking my head over this problem.
HEEEEEELP

I have a server running and it is receiving email just fine. However when trying to send email, it is doing all kinds of funky stuff.
I see timeouts, I see rewrites of the email address of the intended receiver?! for example:
sending from user@mydomain.com to user@otherdomain.com
user@otherdomain.mydomain.com

quote deleted


I have no idea what is happening.

Another piece of log:

Oct 23 21:35:43 ieniemini.dkdl.nl postfix/qmgr[5472]: D950D8699E: from=<sebastiaan@dkdl.nl>, size=990, nrcpt=1 (queue active)
Oct 23 21:35:43 ieniemini.dkdl.nl postfix/qmgr[5472]: F185486736: from=<sebastiaan@dkdl.nl>, size=1048, nrcpt=1 (queue active)
Oct 23 21:35:43 ieniemini.dkdl.nl mail_groups[5460]: no enabled mail groups found
Oct 23 21:35:43 ieniemini.dkdl.nl mail_groups[5460]: sleeping for: 1 hour(s)
Oct 23 21:36:13 ieniemini.dkdl.nl postfix/smtp[5474]: connect to outbounds200.obsmtp.com[207.126.147.11]:25: Operation timed out
Oct 23 21:36:13 ieniemini.dkdl.nl postfix/smtp[5475]: connect to outbounds200.obsmtp.com[207.126.147.11]:25: Operation timed out
Oct 23 21:36:13 ieniemini.dkdl.nl postfix/smtp[5474]: D950D8699E: to=<nepzeb@msn.dkdl.nl>, relay=none, delay=1058, delays=1028/0.03/30/0, dsn=4.4.1, status=deferred (connect to outbounds200.obsmtp.com[207.126.147.11]:25: Operation timed out)
Oct 23 21:36:13 ieniemini.dkdl.nl postfix/smtp[5475]: F185486736: to=<>, relay=none, delay=1958, delays=1928/0.01/30/0, dsn=4.4.1, status=deferred (connect to outbounds200.obsmtp.com[207.126.147.11]:25: Operation timed out)

Could somebody please help me? I have NO idea how to solve this at them moment.