the log is on: http://pastebin.com/bkx4QXnH
In the log are more days ago too and the problem is from about 24. or 25. june to today. You can see all.
The domain is: prostudio.sk, mail server is: mail.prostudio.sk.
I thing it isn't in the domain, while it was working corectly some months.
Is 188.8.131.52 the IP of the machine you are sending messages from? suska.router-3.tvbox.sk does not resolve forward. It does resolve reverse however. Something is misconfigured there.
jaimelm$ host suska.router-3.tvbox.sk
Host suska.router-3.tvbox.sk not found: 3(NXDOMAIN)
jaimelm$ host 184.108.40.206
220.127.116.11.in-addr.arpa domain name pointer suska.router-3.tvbox.sk.
What DNS servers is your OS X Server configured to use? Note that the related parameters in Postfix are called helo_restrictions. In particular, the values reject_invalid_hostname and reject_unknown_hostname. I wouldn't disable those however. I'd fix your DNS.
Whether or not you changed it, the mail server public DNS is incorrectly configured. The reverse translation does not match the forward translation:
$ dig +short MX prostudio.sk
$ dig +short mail.prostudio.sk
$ dig +short -x 18.104.22.168
The ISP with the DNS server for 22.214.171.124 needs to change the response to mail.prostudio.sk.
I have give to recheck it and add the reverse record for mail.prostudio.sk, but at the beginning don't have any reverse records and all was working OK, then I added reverse record only for the domain and all was working some mounth OK, but oknow, I don't do anything on server, I can't become mail from many servers. I found, that I become mails from servers, but with a long delay.
Have you any idea, what it can do?
Here is why you want to fix your DNS...
When your public DNS configuration is incorrect, other DNS servers can decide that you're probably a spam engine, and drop your outbound mail — which you won't get notified on — and can potentially drop mail aimed for your server — which you won't get notified on. In these cases, you will not see any indication of any errors, other than eventually hearing about some dropped mail messages from folks that were trying to communicate with you.
Again, some mail will get routed to you and received from you by mail servers with more tolerant settings, which means things will appear fine. You can enable similar checks in your own mail server, as various folks do. But again, this has absolutely nothing to do with your mail server — which may be working just fine for most mail — this is how other mail servers perceive your server, based on your DNS.
In short: fix the DNS.
There will be a delay in arriving mail as the anti-spam greylisting learns the servers you communicate with. Greylisting can be disabled, but that does mean more spam; greylisting does slow messages, but does not normally cause the loss of any messages among properly-functioning mail servers. Once your mail server communicates a number of times with the particular remote mail server, the greylisting will be automatically bypassed. (This training can be a little longer with a few services such as gmail, as Google has a number of mail servers greylisting will learn about.) When this greylisting case is arising for a particular case, you'll see your mail server returning 450 try again later status to arriving mail from "strange" mail servers, and you can see other servers sending the 450 to you.
That suska.router-3.tvbox.sk address has valid reverse DNS (address to name) but lacks a forward DNS translation; that doesn't look to be a valid mail server, given the DNS errors with it. While that could be a spam engine, those usually don't have valid reverse DNS. It is possible to override the anti-spam and related checks for specific hosts, if you don't have control over the DNS translations for the hosts, and if the translations are invalid.
Obviously, the most expedient approach here would be to outsource your mail service to a provider; to have your domain and email hosted. Make all of this somebody else's problem.
I give to repair the DNS recods. I hope that helps, while I have checked the spam house servers and I'm not there and from that server I'm sending me mails about a half year. It's in office where I work too and no one has problems with it.
I thing there will be another problem too in the settings, while I don't understand while it won't work after some months ...
And I have disabled the graylists.
And I have today become a return mails that sending fails.
The mail system
<email@example.com>: connect to mail.prostudio.sk[126.96.36.199]:25: Connection refused
Reporting-MTA: dns; mail.sunteq.sk
X-Postfix-Sender: rfc822; firstname.lastname@example.org
Arrival-Date: Wed, 26 Jun 2013 12:30:13 +0200 (CEST)
Final-Recipient: rfc822; email@example.com
Diagnostic-Code: X-Postfix; connect to mail.prostudio.sk[188.8.131.52]:25: Connection refused
Received: from localhost (localhost.localdomain [127.0.0.1])
Have you another idea?