On the top part of the Window, you should see comments and a comment button to show/hide comments. The best way to set up SMTP routing is by clicking on the Edit file button, so you are editing the configuration file directly with a notepad.
It is done with an option called Routing, found in Main Menu > Mail > General > Routing tab, as seen below: In that case, you can route all emails to that particular destination/domain through another SMTP server with a different outgoing IP.
Suppose you use this method, but your ISP is blocked at a specific destination. IceWarp will query the DNS servers specified in System/Internet connection to find out the remote system's MX and connect to it directly to send outbound mail. You can find it under the Main Menu > Mail > General > Delivery tab, as seen on the screen below: First of all, it's important to note that IceWarp is usually set up to send out mail using DNS lookups (Use DNS Lookup). There are even systems that block emails from an entire country based on their IP.
Other times, your server's IP might be listed on some DNSBL. If you check the SMTP logs, you will note that you are disconnected right after you connect to a remote system to send an e-mail, which usually indicates the remote system is blocking your IP. Nowadays, unfortunately, it is not rare for a remote system to reject emails from you.
