How does the smtp listener task work on incoming mails?My first idea was, that the smtp listener task only gets the mail header; then the header is checked by the server (smtp inbound control). After a successful checkup the complete mail is received and stored in the mail.box for further sending action.
Is this right?
I’m looking forward to receiving some answers! 
Greets
Jonathan
(sorry for my English)
Subject: How does the SMTP Listener Task work?
I think you mean “does the SMTP listener receive message headers first, then evaluate SMTP inbound restrictions, then accept the rest of the email”.
If that is what you meant then, no. The SMTP listener is looking at the IP address of the connecting host and its resolved name. You can also set inbound restrictions to operate on envelope sender or envelope recipient and to check the IP of the connecting host in blacklists. Only after these checks complete is the entire message including headers received.
It is a common misunderstanding of the way that SMTP works to assume that the delivery protocol treats message contents and header fields differently. It does not. Both form part of the message data (RFC2822). The SMTP listener is operating at the transport level (RFC2821).
Hope this makes sense.