I have an Exchange 2010 server that receives and sends live, without mail relays. His name is remote.<domain>.ch. The domain is hosted by Hostcenter (Swisscom in Switzerland).
The MX is well defined on this server, a spf record exists for this server (with ~ all but not -all) and the query nslookup -q = MX will identify this server.
When sending on all domains that are not hosted at Hostcenter, everything works perfectly.
When sending to a hosted domain at Hostcenter, I have the error below with the direct send connector (port 25, TLS, no relay).
If I send with a relay connector with mail.hostcenter.com and the account that sends the message, I get to send on Hostcenter hosted domains and others.
With such a connector, other users can not send messages with this relayed relay connector at Hostcenter.
If I go through another relay, f the messages are rejected by Hostcenter, if the domain is hosted by HostCenter.
Error message is:
The server mail01.atomia.hostcenter.com rejects all messages with the following error:
mail01.atomia.hostcenter.com #553 5.7.1 <technique@<domain>.ch>: Sender address rejected: not logged in ##
Do you have an idea or have you already encountered the same situation?