SMTP Local Listener reference

SMTP
Select SMTP to allow SMTP clients to send requests over clear-text SMTP.
Specify a Port number. Port 25 is standard. You can also use any other unused port value in the range of 1024 - 65535. Using non-standard ports in the range of 1 - 1023 might interfere with port numbers reserved by TCP/IP for other purposes. 
You can configure SMTP to listen on multiple ports by separating the field values with commas. For example, suppose you specified port 5025, but you have some trading partners who have outbound firewall restrictions and can only send to port 25. Specifying 5025,25 in the Port field allows the firewall-restricted trading partners to be able to send to your server while allowing you to continue to accept inbound messages from your other trading partners on port 5025.
SMTP/s Explicit (STARTTLS)
STARTTLS Optional
STARTTLS Requied
Select SMTP/s Explicit (STARTTLS) and STARTTLS Optional to allow clear-text SMTP trades or SSL trades.
Select SMTP/s Explicit (STARTTLS) and STARTTLS Required to allow only SSL trades.
Specify a Port number. Port 25 is standard. You can also use any other unused port value in the range of 1024 - 65535. Using non-standard ports in the range of 1 - 1023 might interfere with port numbers reserved by TCP/IP for other purposes.
You can configure SMTP to listen on multiple ports by separating the field values with commas. For example, suppose you specified port 5025, but you have some trading partners who have outbound firewall restrictions and can only send to port 25. Specifying 5025,25 in the Port field allows the firewall-restricted trading partners to be able to send to your server while allowing you to continue to accept inbound messages from your other trading partners on port 5025.
SMTP/s Implicit
Select this option to require SMTP/s for all trades.
Specify a Port number. Port 25 is standard. You can also use any other unused port value in the range of 1024 - 65535. Using non-standard ports in the range of 1 - 1023 might interfere with port numbers reserved by TCP/IP for other purposes.
You can configure SMTP to listen on multiple ports by separating the field values with commas. For example, suppose you specified port 5025, but you have some trading partners who have outbound firewall restrictions and can only send to port 25. Specifying 5025,25 in the Port field allows the firewall-restricted trading partners to be able to send to your server while allowing you to continue to accept inbound messages from your other trading partners on port 5025.
SSL Server Certificate
If you select SMTP/s Explicit (STARTTLS) or SMTP/s Implicit, select a valid SSL Server Certificate. Click Browse... to navigate to and select a certificate. Then, enter the Password for the SSL Server Certificate's private key. 
Authenticate Client
Select Authenticate Client to require the SSL client to provide a valid certificate during SSL negotiation.
Authentication Certificates
By default, all of the Certificate Manager Trusted CA and user certificates are accepted for client authentication. To change this, use the Authentication Certificates button to establish the list of accepted FTP client authentication certificates, which can be:
  • all or a subset of the trusted CA certificates and/or
  • all or a subset of the user certificates.
This option must be decided and agreed upon between trading partners before sending messages via SSL. After changing this setting, stop and restart the VersaLex service or daemon to clear cached SSL sessions.
Exchange Certificates
Click Exchange Certificates to send the SSL Server Certificate to your trading partner(s). See Exchanging certificates with your trading partner for further information.