When I try to send an e-mail to the one specific domain I'm getting an error message:

Primary target IP address resonded with: 554 policy violation. attempted failover to alternate host, but that did not succeed etc..

I have no problems with sending e-mails to most of the domains, exepct this one

What might that be?

Thank you in advance

Hi

What settings do you have on your send connector?

Hi 

I think this seems to be a problem at the receiving end 

Things that might be wrong on your end as well which you need to check below 

Do a (rDNS, telnet to your server to check the FQDN and IP Blacklists check)
Try creating a dedicated send connector for this domain alone for this address space alone and see the results . Select the option offer basic authentication only after starting TLS and see the results 
Check in your fire wall if this type of connection "Private command : X-ANONYMOUSTLS" SMTP Policy Restrictions is set . You should make the modifications to the firewall to allow this traffic.
In your case i think mostly it should be the fire wall not allowing X-AnonymousTLS type connections 

Also 

The value  that is set on the Send Connector. It should match the external host name that resolves to your external IP address AND have set as the PTR on the IP address. 

Hello and thank you for the answer,

1.I did Reverse DNS and my Ip address resolves to the name without any errors

2. Telnet is also working with no problems

3. Checked  DNS Blacklists and did not find anything suspicious

Also I forgot to mention that e-mail flow goes through Edge transport server and I have two send connectors which were created automatically during Edge synchronization.

Do you want me to create additional send connector and make my edge server as a source server and in the address space type the name of the domain which I can't send any messages? Am I right?

Thank you

Hello,

1. Delivery: in network settings I have MX record associated with recipient domain
2. Scopping: in Address space: Type is SMTP, Domain is *, Cost is 100
3. Source server is my Edge trasport

Hi,

If the issue persists, I recommend you create another send connector for this problematic domain only and check the result. What's more, please check if your Exchange server is configured to prevent sending messages to this problematic domain.

Hope this can be helpful to you.

Best regards,

Hello,

Eventually, it turned out to be a problem on other side. I've contacted the support team and they added me to their unblocked list. They explained it that their system has high security policy.

Thank you for your assistance